<asp:Button ID="btnFresh" runat="server" Text="" OnClick="btnFresh_Click" />

<script type="text/javascript">
function btnFreshData() {
document.getElementById("btnFresh").click();
}
</script>

ClientScript.RegisterStartupScript(Page.GetType(), "", "<script language=javascript>window.opener.btnFreshData();window.open('','_self');window.close();</script>");