get that amount lowered through negotiations?
If you have a valid promissory note, I am not aware of any statutory review process made especially for these notes. You entered into a contract when you sold the home, and the terms of the short sale agreement will control. I would review that agreement to see what terms it has as far as modification of the promissory note.
That said, it is possible to renegotiate a contract through negotiations, if both parties agree to the terms. There are not enough facts here to determine if any negotiatoin would be successful, because assuming you have sufficient financial means to pay the note the holder of the note would only be bidding against himself. If the holder of the note doesn't agree to the modifications you could stop paying, and invite a lawsuit, or bring a lawsuit yourself. I wouldn't advise either of these without serious consideration and a consultation with legal counsel who will review all the facts and circumstances.
The short answer is anything is possible, but both parties must be motivated to entered into negtiations. Given that your lender already has an enforceable note the odds are probably against it. I agree with the answer of the other lawyer. It would be important to retain an attorney to review your best options.