Unless you have a provable agreement, which usually means a written one, you have no right to get back past living expenses.

But you definitely do have a right to be repaid that loan. First, figure out how much he still owes you. Second, ask him in writing to pay you back. Third, if he refuses to pay, think about how you can prove that you made the loan -- for example, you may have a canceled check or a witness who heard the two of you talk about it. Fourth, assuming you have at least some proof, sue in small claims court. For help in preparing and presenting your case, see Everybody's Guide to Small Claims Court (Nolo).