Both attorneys who have answered, have given you accurate information. I would recommend speaking with them to work out a different payment plan, but if you don't work, I don't know how that is feasible. If you cannot work things out, your choices are limited if you don't have funds to pay an attorney. You can always check with Legal aid.
The decision maker will seek court permission to withdraw from your case. No one is expected to work for free. She or he probably has good reason to insist that the retainer be replenished in full. As many people get burned in the legal profession by being financially stiffed by clients. If you don't borrow it or take out a loan, expect a Motion to Withdraw as Decision Maker next week. That is simply how it works.
The information provided in this answer does not create an attorney-client relationship. If you are interested in his legal services, feel free to call Chris at (303) 409-7635 at his law office in the Denver Tech Center. All initial consultations are free of charge.
Mr. Leroi is correct -- the DM will ask the court for permission to leave the case.
In no way am I offering you legal advice, and in no way has my comment created an attorney-client relationship. You are not to rely upon my note above in any way, but insted need to sit down with counsel and share all relevant facts before receiving fully-informed legal advice. If you want to be completely sure of your rights, you must sit down with an experienced criminal defense attorney to be fully aware of your rights.