Issue with page event when RegisterStartupScript has been used

Hi dear experts,

I am facing a problem and i need some help, please have look 

I have aspx page with Ajax popup control and update panels, Aspx page contains a user control and Event Handler, a web user contol has submit button and when submit button clicked the page Event fires and fill the grid again with modified changes on aspx page. 

on web user control when submit button clicked then bellow code executes and call another page of aspx which contains the code to export the Report file to word formate.

ScriptManager.RegisterStartupScript(this.upnlResult, upnlResult.GetType(), "newWindow", "window.open('../myfolder/letters.aspx','','fullscreen=no,toolbar=no,left=0,top=0,status=no,menubar=no,resizable=no');;", true);

the above code works fine for the web user control when submit button clicked, export the report file to word, then event fires and fill the grid again on aspx page with modified changes. 

another button which is on main aspx page also used for the same purpose to export the data into word format and call the same ScriptManager.RegisterStartupScript() as mentioned above but issues that when I click on aspx page button (not user control button) then report exports successfully but grid not updated and it contains all the old values.

I try to use the same event to fill the gird again but it does not work, i created the fill grid method and simply call after the ScriptManager.RegisterStartupScript() but it also did not work because control already transfers to another page in this case"letters.aspx". 

I think in this case event only used for the web user contorl, not for the another aspx page.

please help

Thanks