Hi Ashok,The viewer is just that, a viewer. Think of it like the free Adobe .pdf reader. It's designed to serve up data that's already been exported, not to refresh data. The only time you can refresh a report is if you have some flavor of Enterprise Software (Enterprise, Edge or Crystal Reports Server) and you have a User ID for that system. In that situation, you can open a report from the repository and refresh it, assuming you have permissions to the report.
Please read the [Release Notes http://help.sap.com/businessobject/product_guides/crv2008/en/xi3-1_crviewer_release_en.pdf] document for further details.