I'm not sure how much your dues are per person, but here are a couple of ideas (depending on how much the dues are, they might not work):
1. Set up payment plans for those who cannot pay all at once, or have everyone pay a little bit each month in anticipation of your deadline for dues so that the money will be there when you have to turn it in.
2. Have some fundraisers specifically for dues so that the out-of-pocket cost per sister is reduced. You might even be able to raise all the dues for the chapter by fundraising.
Good luck!
