The procedure to update the AIX policies is documented in the User Guide, and we also have a KB for it:
KA350902 - AIX Catalog Update setup: Cannot find latest SP and TL levels in the filters
Does AIX patching still use the downloader? Is the issue that you need to run the downloader again to get the new patches to create a catalog from?
Starting 8.2, you can create the Online AIX Catalog - no need for offline downloader like you did in previous releases.