SSRS URL ReportSession keeps breaking

 I am displaying an SSRS graph in SharePoint and it works for about an hour until the link breaks.  This is caused by the ReportSession changing. 

I ran across a fix for the ControlID:

ControlID={{QueryStringParam2.ExecutionID}}

I need to know if I can do something similar for ReportSession

Here is my link:

http://ServerName/Reports/Reserved.ReportViewerWebControl.axd?ReportSession=ruvotw45hfcfh5555d4tsn55&ControlID={{QueryStringParam2.ExecutionID}}&Culture=1033&UICulture=9&ReportStack=1&OpType=ReportImage&StreamID=C_3iS0T0_1

Help....

Always in need of help.