Losing data after postback in ASP.net C#

i'm binding datalist control from database in !page.ispostback page event, when i hit any button the page postback and i lose datalist data source,so what i shall do to prevent losing data? deplucate the code in postback event or what?

  protected void Page_Load(object sender, EventArgs e)
{

    
    if (!Page.IsPostBack)
    {
        try
        {
            Session["ClinicID"] = "1";
            c.FillDataList(DataList1, "SP_GET_PATIENTS_LIST", "@CLINICID", int.Parse(Session["ClinicID"].ToString()), lblmsg);
            updPatientsList.Update();
        }
        catch (Exception)
        {

        }
    }
}