Ko4life could try dabbling in other games. Just because users have left KO, doesn't mean they don't know people who still play. If you made other game sections I think the forum would retain some of the users who have left. (Add moderators to those respective games). i.e. WoW, Dota, snooker, CS, etc. As of now, Ko4life has essentially one direction -> Knight Online (coincidence!). Therefore, your forum is somewhat dependent on K2's efforts (not that great). If you guys have $20 lying around, make some redirections like WOW4life, dota4life to bounce to ko4life. Meh.
Most of the people who have come and gone in KO played because of other people.