§ 68. Advances to county self-insurance fund. If at any time there are insufficient moneys in the county self-insurance fund, exclusive of the reserve, to operate the plan, the county treasurer shall advance to such fund such amount from the general fund of the county, as shall be requested by the committee or administrator and approved by resolution of the board of supervisors. Any such advance shall be repaid as soon as moneys are available therefor, but in no event later than the close of the calendar year succeeding the calendar year in which the advance was made. However, any such advance may be repaid not later than the close of the second calendar year succeeding the calendar year in which such advance was made, when made during such calendar year at a time subsequent to the preparation of the estimate by the committee or administrator for the succeeding calendar year.