(1) Except as otherwise provided in this act, if a member separates or is separated from state service without leave of absence before becoming eligible to retire with a retirement allowance payable from funds of the retirement system, the member ceases to be a member and forfeits credit for all service rendered by him or her before the date the member last separated from state service.

  (2) If the individual again becomes employed by this state, he or she shall again become a member of the retirement system.

  (3) An employee who reenters state service within 15 years after the date of his or her last separation from state service, or who accumulates 5 or more years of continuous service credit as a member of the retirement system after reentering state service, shall have the service credit forfeited by him or her at the time he or she last separated from service restored to his or her credit, if the member has not withdrawn his or her accumulated contributions from the employees’ savings fund. If an employee described in this subsection has withdrawn his or her accumulated contributions from the employees’ savings fund, the member shall have the service credit forfeited by him or her restored to his or her credit if he or she returns to the fund all amounts that were previously withdrawn from the fund, together with regular interest on that amount computed from the date of withdrawal to the date of repayment.

  (4) If a member becomes a retirant or dies, he or she ceases to be a member.