A disability retiree from any division whose disability application was received by the association prior to January 1, 1999, may be employed by an employer, whether or not in a position subject to membership, without any reduction in benefits pursuant to the terms and conditions specified in sections 24-51-1101 to 24-51-1103 and in section 24-51-707. However, if the disabling condition returns, the disability benefit may begin again upon the application of such member and approval of such application by the board.