My chapter was in the same spot you guys are in about four years ago. We used to sit down and have brain storming parties about what we could do to get our name out on campus more.
Some things we did:
1. Bake cookies for all the fraternities and sororities during finals
2. Did a window wash in the school parking lot with notes that said "your windows were washed by KayDee!"
3. Constantly contacted other organizations for mixers, etc
4. Made sure we were out en masse for other groups philantrophies and such events.
5. We would have letter making parties where we would brain storm on cute letter designs. I firmly believe that by the time I graduated we had the cutest letters. Too often they're just put on a sweatshirt and noone really notices them. We would go to cheap but nicer stores and buy fitted tees in different colors and put letters on them. We also just worked to have different styles than the other sororites. I really believe this helped us stand out more and it especially helps during recruitment because even the freshman notice them more
Hope some of that helps.