I had to renew mine and change my address in 2003 after not having used it in a few years. They had lost my 2002 Renewal and I lost the returned check (so of course I got beat out of the money!!!), but you can get the idea as to what you have to write and do from the letter below...And, no, you do not have to retake the test.
Here is the Letter that I sent w/required info. and attachments:
To: NJ Fish & Wildlife Date: 07/31/03
P.O. Box 431
Trenton, NJ 08625
Subject: NJ Rifle Permit Renewal
To whom it may concern,
Enclosed you will find a copy of one of my previous NJ Rifle Permits, SS #, DOB, and a new check for $19.00. In reference to my phone call to your office and your return voicemail message earlier this week, I was unable to retrieve the cancelled check for a permit renewal that was sent to your office and cashed last year in the Sept./Oct. 2002 timeframe.
If possible, when this submittal is received by your office, please call any of the numbers provided to confirm that you have received the enclosed.
Thank you for your time and cooperation.
SS #: XXX-XX-XXXX
Encl: Copy of previous NJ Rifle Permit w/ change of address info. AND Check # 2390 for the amount of $19.00