The board may repay the district for any advance of funds from the proceeds of the sale of bonds authorized for the purposes of the improvement district or as provided in Section 71616. To the extent that advances made for improvements for which such bonds were authorized are repaid from the funds other than the proceeds of the sale of bonds of the improvement district, the authority of the board to issue bonds of the improvement district in a like amount or amounts shall terminate. The treasurer shall maintain proper records and accounts in which there shall be set forth all repayments of advances to the extent that advances are made for the improvements for which such bonds were authorized and, to the extent that such repayments reduce the amount of bonds which may be issued on behalf of any improvement district, the net principal amount of authorized but unissued bonds of such improvement district.