N.J. Stat. § 43:13-22.32
When a member of the retirement system is separated from service or is absent on leave for a period in excess of 1 year, and said separation or leave of absence is for a cause other than illness or other employment within the municipality covered by the retirement system, then and in such event the commission may remove such member from the membership rolls of the system, whereupon the said member shall be entitled to receive a refund of his contributions to the system in accordance with section 29 of this act. Whenever a member of the retirement system shall be on leave of absence or becomes separated from the municipal service for any reason other than retirement or entry into the armed forces and subsequently re-enters the service of the municipality within 5 years after such separation and shall submit to and pass the physical and mental examination required by the commission as provided under section 13(a) of this act, then all the rights and benefits hereunder enjoyed by such member prior to such separation shall be restored to him upon payment of any refunds given to him at the time of his separation from the service; provided, however, that such member shall not be entitled to receive credit for pension purposes for the time elapsing during such separation period; and provided, further, however, that such member or his dependents or beneficiaries shall not be entitled to receive any pension benefits during such separation period. Such repayment of refunds may be made either (1) in one sum or (2) the total amount together with 3% interest on said total amount by regular payroll deductions over a period of not more than 10 years, but in no event to extend beyond the date upon which such employee attains the age of 60 years, such installments to be deducted in addition to the other deductions made from his salary for the retirement system. The municipality shall not be required to make a matching contribution for such repayment.
N.J.S. § 43:13-22.32