In Cognos 8 MR2 and higher you can update all objects based on a package by creating a 'Report Upgrade Task' from within Cognos Connection.   
In order to do this go to:
- Tools / Content Administration      / ‘New Report Upgrade' from within the new content maintenance      dropdown in the button bar.
 - Enter a name that represents      the objects that you will upgrade
 - Select the items that you want      to upgrade by navigating to their folder location and adding them to the ‘selected      entries’ panel on the right side.
 - Click OK / Next / Finish
 - Click Run if you want to      execute this task now
 - [I always check the box for      view details] / Click OK