...at least make a new server for it. That way you still have a minor chance that fresh meat would stay for some time. Maybe make old players to get like 5hrs worth of grinding in gold daily on login. Or revert old server to prerevamp state - since owls so far failed to resurrect any of bgs killed with the revamp. Or just turn it into a test server or something.
Revamps are always hard.. the revamp before this one was not that easy too.. BGs were put from 20 runes to 30 runes per bg