It sounds like y'all might want to tear a page out of the fraternity rush book. Ask guys that are in houses to steer girls they know that aren't in houses your way. Talk to people in the dorms. Do any kind of PR that your PHC allows. Just get the word out that you do exist and you all have something very special.
I don't think that there's any campus out there that can change in such a way that it ever needs to contract in terms of the # of GLO's on campus. The only reason that ever happens is because the GLO's on campus do not adjust correctly to the changes in the types of people they need.
Whatever you do though, you have to change something
I'd be afraid to talk to your HQ though. How quick are they to shut down chapters that they claim to be 'defunct'?