jqplot - Export jqplot within the update panel

Question

I have graph in my page, build with the help of jqplot. And the graph lies within the update panel.Now I need to export that graph to the excel. But while I export that graph only the Title get exported but not the graph.So, I am stuck on this.

I will be very thankful to the answer for exporting the chart build by jqplot within the update panel to excel

Code used for export:

protected void btnExcel_Click(object sender, ImageClickEventArgs e)
{
    Response.Clear();
    Response.AddHeader("content-disposition", "attachment;filename=ProjectTarget_" + CampaignID + ".xls");
    Response.Charset = "";
    Response.ContentType = "application/vnd.xls";
    StringWriter stringWrite = new StringWriter();
    HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

    //  LoadMileStones(currMileStone);

    TableLists.RenderControl(htmlWrite);
    Response.Write(stringWrite.ToString());
    Response.End();
}