N.J. Stat. Ann. § 20:3-25

If within 6 months from the date of appointment of commissioners, the condemnor fails to file a declaration of taking, the court, upon application of any condemnee, and on notice to all parties in interest, may require the condemnor, at its election, to either file a declaration of taking and make the deposit hereinabove provided, or abandon the proceedings pursuant to section 35 hereof. For good cause and upon terms, the court may extend the time for the filing of such declaration of taking, but not more than 3 months after the commencement of the action.