I found an answer for this problem you can use,
<asp:updatepanel runat="server" xmlns:asp="#unknown">
<contenttemplate>
<asp:timer id="Timer1" runat="server" interval="1000" ontick="Timer1_Tick"></asp:timer>
<asp:repeater runat="server" id="rptOffers" onitemdatabound="rptOffers_ItemDataBound">
<itemtemplate>
<asp:label id="Label3" runat="server" text="<%#Eval("DueDate") %>" visible="False">
</asp:label>
<asp:label id="Label1" runat="server"></asp:label>
<asp:label id="Label2" runat="server" />
</itemtemplate>
</asp:repeater>
</contenttemplate>
<triggers>
<asp:asyncpostbacktrigger controlid="Timer1" eventname="Tick" />
</triggers>
</asp:updatepanel>
and CodeBehind you use this block
protected void Timer1_Tick(object sender, EventArgs e)
{
foreach (RepeaterItem item in rptOffers.Items)
{
var label2 = item.FindControl("Label2") as Label;
var label3 = item.FindControl("Label3") as Label;
var time2 = DateTime.Parse(label3.Text);
label2.Text = (time2 - DateTime.Now).Days + " " + (time2 - DateTime.Now).Hours + " " + (time2 - DateTime.Now).Minutes + " " + (time2 - DateTime.Now).Seconds + " ";
}
}