Can I negotiate with auto lender when in bankruptcy?

I refinanced an auto loan in 12/04. I recently filed bankruptcy (cht. 7) and the lender sent me a notice to send them the balance which is 4600 within the next 10 days. I want to keep the car but cannot afford to pay it off and need the lowest payment possible to reaffirm the loan. Is there any room for negotiations or is the ball in their court. Payments are 281 per month and i havent paid since august 07. Please help me ASAP in NJ. I did bankruptcy myself