برای اینکه این عملیات بدون بازسازی صفحه انجام بشه از کنترل های Ajax خود دات نت استفاده کردم:
کد کل صفحه:

<%@ Page Language="C#‎" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script language="javascript" type="text/javascript">
function FilterEnterNumber(e, maxValue)
{
var keyCode = e.value.charCodeAt(e.value.length - 1);
if(keyCode < 48 || keyCode > 57)
{
e.value = e.value.substring(0, e.value.length - 1);
e.focus();
return false;
}
if(maxValue != null && maxValue != undefined)
{
if(parseInt(e.value) > maxValue)
{
e.value = maxValue;
}
}
}
</script>
</head>
<body>

<form id="form1" runat="server">
<div align="center">

<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdateProgress ID="UpdateProgress1" runat="server">
<ProgressTemplate>
<asp:Label ID="Label9" runat="server" Text="چند لحظه صبر کنید"></asp:Label>
</ProgressTemplate>
</asp:UpdateProgress>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" RenderMode="Inline" UpdateMode="Always">
<ContentTemplate>

<asp:GridView ID="GridView1" runat="server"
AutoGenerateColumns="False" ondatabound="GridView1_DataBound"
BackColor="White"
BorderColor="#E7E7FF" BorderStyle="None" BorderWidth="1px" CellPadding="3"
GridLines="Horizontal" EmptyDataText="جدول خالی میباشد" Font-Bold="False"
Font-Names="Tahoma" Font-Size="Small" Width="70%"
>
<AlternatingRowStyle BackColor="#F7F7F7" />
<Columns>
<asp:BoundField DataField="display_name" HeaderText='نام شهر' ItemStyle-Width="50px" >
<ItemStyle Width="50px" HorizontalAlign="Center" VerticalAlign="Middle"></ItemStyle>
</asp:BoundField>
<asp:BoundField DataField="id" HeaderText='شناسه' ItemStyle-Width="50px" >
<ItemStyle Width="50px">
</ItemStyle>
</asp:BoundField>
<asp:TemplateField HeaderText='ردیف' HeaderStyle-Width="40px">
<ItemTemplate>
<asp:Label runat="server" ID='lbl' Width="25px" Height="25px" Text='<%# Eval("RowNum") %>'/>
</ItemTemplate>
<HeaderStyle Width="40px"></HeaderStyle>
</asp:TemplateField>
</Columns>
<FooterStyle BackColor="#B5C7DE" ForeColor="#4A3C8C" />
<HeaderStyle BackColor="#4A3C8C" Font-Bold="True" ForeColor="#F7F7F7"
HorizontalAlign="Center" VerticalAlign="Middle" />
<PagerStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Right" />
<RowStyle BackColor="#E7E7FF" ForeColor="#4A3C8C" HorizontalAlign="Center"
VerticalAlign="Middle" />
<SelectedRowStyle BackColor="#738A9C" Font-Bold="True" ForeColor="#F7F7F7" />
<SortedAscendingCellStyle BackColor="#F4F4FD" />
<SortedAscendingHeaderStyle BackColor="#5A4C9D" />
<SortedDescendingCellStyle BackColor="#D8D8F0" />
<SortedDescendingHeaderStyle BackColor="#3E3277" />
</asp:GridView>

<br />
<asp:Table ID="Table1" runat="server" Font-Names="Tahoma" Font-Size="Small">
<asp:TableRow ID="TableRow1" runat="server">
<asp:TableCell ID="TableCell1" runat="server"><asp:ImageButton ID="btnStart" runat="server"
ImageUrl="~/Images/1322728593_control_start_blue.png"
onclick="btnStart_Click" /></asp:TableCell>
<asp:TableCell ID="TableCell2" runat="server">
<asp:ImageButton ID="btnPrevious0" runat="server"
ImageUrl="~/Images/1322728647_Play1Pressed - Copy.png"
onclick="btnPrevious0_Click" /></asp:TableCell>
<asp:TableCell ID="TableCell3" runat="server"></asp:TableCell>
<asp:TableCell ID="TableCell4" runat="server"><asp:TextBox ID="txtPageNumber" runat="server" Text="1" ontextchanged="txtPageNumber_TextChanged"
Width="25" AutoPostBack="True" onkeyup="FilterEnterNumber(this,10000)"></asp:TextBox> </asp:TableCell>
<asp:TableCell ID="TableCell5" runat="server">
<asp:ImageButton ID="btnNext" runat="server"
ImageUrl="~/Images/1322728647_Play1Pressed.png" onclick="btnNext_Click" />
</asp:TableCell>
<asp:TableCell ID="TableCell6" runat="server"><asp:ImageButton ID="btnEnd" runat="server"
ImageUrl="~/Images/1322728537_control_end_blue.png" onclick="btnEnd_Click" /></asp:TableCell>
</asp:TableRow>
</asp:Table>
<asp:Table ID="Table2" runat="server" Font-Names="Tahoma" Font-Size="Small">
<asp:TableRow ID="TableRow2" runat="server">
<asp:TableCell ID="TableCell7" runat="server">رکورد</asp:TableCell>
<asp:TableCell ID="TableCell8" runat="server">
<asp:Label ID="Label8" runat="server" Text="Label" BackColor="BlanchedAlmond"></asp:Label></asp:TableCell>
<asp:TableCell ID="TableCell9" runat="server">از</asp:TableCell>
<asp:TableCell ID="TableCell10" runat="server">
<asp:Label ID="Label7" runat="server" Text="Label" BackColor="BlanchedAlmond"></asp:Label></asp:TableCell>
<asp:TableCell ID="TableCell11" runat="server">تا</asp:TableCell>
<asp:TableCell ID="TableCell12" runat="server">
<asp:Label ID="Label6" runat="server" Text="Label" BackColor="BlanchedAlmond"></asp:Label></asp:TableCell>
<asp:TableCell ID="TableCell13" runat="server">پیمایش رکودهای</asp:TableCell>
<asp:TableCell ID="TableCell14" runat="server">-------</asp:TableCell>
<asp:TableCell ID="TableCell15" runat="server">
<asp:Label ID="Label5" runat="server" Text="Label" BackColor="BlanchedAlmond"></asp:Label></asp:TableCell>
<asp:TableCell ID="TableCell16" runat="server">از</asp:TableCell>
<asp:TableCell ID="TableCell17" runat="server">
<asp:Label ID="Label4" runat="server" Text="Label" BackColor="BlanchedAlmond"></asp:Label></asp:TableCell>
<asp:TableCell ID="TableCell18" runat="server">نمایش صفحه</asp:TableCell>
</asp:TableRow>
</asp:Table>
<br />
<br />
<asp:Label ID="Label1" runat="server" Text="Label" Visible="False"></asp:Label>
<br />
<asp:Label ID="Label2" runat="server" Text="Label" Visible="False"></asp:Label>
<br />
<asp:Label ID="Label3" runat="server" Text="Label" Visible="False"></asp:Label>

</ContentTemplate>
</asp:UpdatePanel>
</div>
</form>
</body>
</html>