Trying to update gridview in updatepanel using jquery every n seconds

I would like to update the following gridview every 5 seconds. I thought I could use javascript to call the postback, which runs, but never hits the code behind. I tried mapping this to a button and calling the .click event, but that did not work either. I think I am close -- can someone nudge me along?

    <asp:UpdatePanel ID="udPanel2" runat="server" UpdateMode="Conditional">
        <ContentTemplate>
            <h3>Waiting to Sync</h3>
            <asp:LinkButton ID="lnkbtnRefreshXREF" runat="server" Text="Refresh" ToolTip="Refresh" CssClass="syncbtn"></asp:LinkButton>
            <asp:GridView ID="gvXREF" runat="server" GridLines="None" CssClass="gv" AlternatingRowStyle-CssClass="gvalt" AutoGenerateColumns="false" ShowHeaderWhenEmpty="true">
                <Columns>
                    <asp:BoundField HeaderText="Stop ID" DataField="STOP_ID" />
                    <asp:BoundField HeaderText="Customer ID" DataField="WHOLE_ACCOUNT_ID" />
                    <asp:BoundField HeaderText="Nickname" DataField="NICKNAME" />
                    <asp:BoundField HeaderText="Name" DataField="NAME" />
                </Columns>
            </asp:GridView>
        </ContentTemplate>
    </asp:UpdatePanel>

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    <script>
        $(document).ready(function () {
            var t = 5
            if (t > 0) {
                // ### Start Page Reload Timer
                var iTimeRemaining = t;
                window.setInterval(function () {
                    if (iTimeRemaining == 0) {
                        //Post Back
                        setTimeout('__doPostBack(\'<%= lnkbtnRefreshXREF.ClientID%>\',\'\')', 0);
                    } else {
                        iTimeRemaining = iTimeRemaining - 1
                    }

                }, 1000);
            }
        });
    </script>

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    Protected Sub lnkbtnRefreshXREF_Click(sender As Object, e As EventArgs) Handles lnkbtnRefreshXREF.Click
        PopulateLandmarkXREFGV()
    End Sub