13.1. Should any member leave City employment, for any reason except his retirement or death, he shall thereupon cease to be a member and his credited service in force at that time shall be forfeited by him except as otherwise provided in Section 15 or Section 20 of this Article. In the event he again becomes an employee of the City he shall again become a member. His credited service or a portion thereof last forfeited by him shall be restored to his credit; provided he returns to the employees’ savings fund the amount, he withdrew therefrom or a portion thereof equal to the service sought to be credited together with regular interest from the date of withdrawal to the date of repayment. Payment of a portion of withdrawn contributions plus interest will restore that portion of credited service to the employee’s account pursuant to policies established by the retirement board. Credited service shall not be restored to a member until he has returned to the employees’ savings fund the full amount, including interest, herein before required of him in this section. In the event a member becomes a retirant or dies he shall thereupon cease to be a member.