Hi Neha,
I'm not sure what you mean by refresh.
Take a look at the Information Steward Administrator's Guide (found at http://help.sap.com/bois). Refer to section '5.5 Repository utility overview' which details how to use the ISRepositoryUtility. Section 5.5.3 specifically addresses manually upgrading an existing IS repository. Hope that helps.
Regards,
Vlad
