SEPM 12.x cannot update SEPM 11.x version.
If you needed to replication it's must be required same version both side.
Symantec does not support multi-version manager replication scenarios. Database schemas can change from version to version, and database corruption could occur if the schemas do not match. All Symantec Endpoint Protection sites that replicate should be running the same version.
Does Symantec Endpoint Protection Manager support replication between sites running different versions?
http://www.symantec.com/docs/TECH92235
Edit
See this thread
http://www.symantec.com/connect/forums/replication-between-sites-sepm-121-ru2-mp1-and-sep-121-ru1-mp1ru2