Is there any other way to preview with out using a APP for the _reportpreivew system variable?
my reqiurement is like i should not have a seperate source for this APP line the ReportPreview. i have to have the source in my basic project and use reportlistener for previewing the reports.

You have a couple of options. You can follow the instruction in the help file:
How to: Specify and Distribute ReportPreview.App

Or you can write your own preview from scratch:
Techniques for an alternative Report Preview UI

Have fun!