The remarriage of a surviving spouse shall not render the surviving spouse ineligible to receive a retirement allowance described in section 27 or 31(c). A surviving spouse whose retirement allowance described in section 27 or 31(c) was terminated due to the surviving spouse's remarriage shall be eligible to receive that allowance beginning on the first day of the month following the month in which written application for reinstatement is filed with the board, but shall not be eligible to receive the allowance attributable to any month beginning before the month of reinstatement under this section.