Let me clarify– You were put in the RTP because you were on the 2013 National Team. After the 2014 team is named, all those who were on the 2013 team, and not the 2014 team will be removed from the RTP (so, if you don't make the team in 2014, you would
no longer qualify for the RTP). Since you are only qualifying for the RTP this year, you would only need to re-enroll this year, if you chose to continue rowing. In 40 years, you wouldn't qualify for the RTP in the first place, not having been on a team for
40 years, so you would not have to re-enroll in the pool.
You should only be retiring from the pool if you are truly retiring from the sport. Recreational coxing in 40 years is fine. If you are planning to cox at any USRowing sanctioned event this year, I would definitely re-think your intentions to retire.