How to avoid the Page Refresh when date selected time

Question

Here is my code for select a date in Text box,when i select a date Adds the 5 days in the grid view label column below i am coloured the label,5 days adds correctly using TextChanged event, but one problem is every time the page is refresh how avoid if know share me!

 

Thank You

 

<ItemTemplate><asp:UpdatePanel runat="server" ID="UpId"

UpdateMode="Conditional" ChildrenAsTriggers="true">

<ContentTemplate>

<asp:TextBox ID="txtScheduleDate" runat="server" CssClass="txt" Width="100px" Text='<%#Eval("schedulePickDate")%>' OnTextChanged="txtScheduleDate_TextChanged" AutoPostBack="true"></asp:TextBox>

<asp:CalendarExtender ID="CaltxtScheduleDate" Format="dd-MM-yyyy" runat="server" TargetControlID="txtScheduleDate">

</asp:CalendarExtender>

</ContentTemplate>

</asp:UpdatePanel>

</ItemTemplate>

<asp:TemplateField Visible="true" HeaderText="EPD">

<ItemTemplate>

<asp:Label ID="lblEpd" runat="server" Text='<%#Eval("epd")%>'></asp:Label>

</ItemTemplate>

</asp:TemplateField>