Vacancies in the membership of the board shall be filled as follows:
Each member so appointed shall serve until the organizational meeting following the next annual election unless the member is appointed to fill a vacancy occurring within the 60 days immediately preceding such election if the annual election is held in April, or occurring after the third Monday in July if the election is held in November, to fill a term extending beyond such election, in which case the member shall serve until the organizational meeting following the second annual election next succeeding the occurrence of the vacancy, and any vacancy for the remainder of the term shall be filled at the annual election or the second annual election next succeeding the occurrence of the vacancy, as the case may be.
N.J.S. § 18A:12-15