Simple stuff:
This week, on thursday, you should do a snapshot of the database, go grab everyone who ever got a single month worth of subscription, and mark them all as Veteran accounts (for PS2 beta).
Then, once that snapshot is done and the accounts are marked, you deactivate the ability to subscribe and add unlimited free game time to everyone who got marked as a vet. Remove the ability to buy the game, and dont let any new guys in at all. This is to prevent cheaters flooding the server. Add some GMs to the mix monitoring appeals to get rid of those who still try to cheat.
Then, let it run till PS2 release, and check again how many stay in PS1. If they cant even get a half decend fight going during prime time at a weekend, kill it. Otherwise, let it run till people finally leave.
This would boost Planetside Day to level crazy, and give every vet something to play till he gets into the beta, or in case beta servers are down for whatever reason. It also allows us to have those giant battles and several poplocks for some more time.