N.J. Stat. Ann. § 40:41A-23

Whenever the question of whether to adopt one of the optional forms of government provided in articles 3, 4, 5 or 6 of this act shall have been placed before the voters of a county in a referendum at a general or special election, no subsequent referendum question to change the form of government shall be submitted to the voters until not less than 3 years shall have elapsed after the effective date of the optional form approved by the voters, or, in the case of a proposed change which was defeated at a referendum election, until 3 years shall have elapsed after the date of the election.