Forget the flouncers. The only "work" to do on them is to make sure they know through the campus grapevine that the girls who stayed are having a wonderful, supportive and life-changing sisterhood experience - which they threw away because they didn't get "top tier." If they want it, they need to come begging to you, not the other way around. Plus nothing will make you guys look more desperate than chasing after people who you invited to your home and were rude enough to not even show up and give it a try. Take Cee-Lo's advice on this one
We say to PNMs - the houses that dropped you during rush don't exist any more, the only ones that exist are the ones you still have left. It works both ways. Love and cherish the NMs who are enjoying being there, and they will let their friends know, and so on, and so on. You need women right now who want YOUR sorority, not just A sorority. Good luck!!