Email the financial aid office and ask if they have a financial aid appeal process. I would avoid using the word "negotiate" as financial aid offices are audited.
Once you know what the appeal process is, you either fill out a form or in some cases, you end up calling the financial aid officers and explaining your situation. There's usually wiggle room to give you more $, but do it sooner rather than later while there still are funds before its all appealed away.