That's an odd policy. At the many universities where I took postbacc courses, summer class financial aid belonged to the academic year preceding it and wouldn't impact the following year's financial aid.
Some thoughts:
- Are you registering as a degree-seeking undergraduate? This is necessary at many schools to receive maximum aid, even if you aren't degree seeking. This is what I was instructed to do by the academic advisors and financial aid advisors at the schools where I did my postbacc. At the one school where I didn't register as a degree-seeking student, my tuition was higher and my financial aid was lower.
- Different universities have different financial aid policies, even within the same state. If you have other instate options, talk to their financial aid departments.
- If you can't work out the federal financial aid loans, take out private loans. You'll need a credit-worthy cosigner though, which not everyone has.
- There's always credit cards. I proudly hold a $10k credit card balance - proudly because it got me into medical school (and I'm making my minimum payments, of course).
- But in the end, if you'll start getting loans again next fall, it won't be the end of the world if you can't resume classes till then. You can just work and volunteer until then, building other parts of your app.