N.J. Stat. Ann. § 3B:10-15

When a sole or sole surviving or remaining executor or administrator, with or without the will annexed, dies or is removed or discharged by the court after qualifying and entering upon the duties of his office but before the completion thereof, the vacancy so created shall, except as hereinafter provided, be filled by the appointment of a fit person to exercise the vacated office. The person so appointed shall be nominated substituted administrator with the will annexed or substituted administrator, as the case may be.