I would suggest cbp.gov:
For general CBP inquiries, please call the CBP INFO Center Monday-Friday, between 8:30 a.m. and 5 p.m. Eastern Time.
General Inquiries: 1-877-CBP-5511
International Callers: (703) 526-4200
and whatever they tell you on the phone
, ask them where you can confirm what they say online, or if they can send you a written confirmation.
Last I had heard, the policy was one year, not one day longer, and that you had to exit the US for 14 days and enter another nation's waters before you could return and apply for a new permit.
It is possible that if you are having "necessary repairs" or the boat is hauled in a yard (so it is not in US waters) that there's some provision for grace. After all, there are treaties and such for vessels delayed for necessary repairs
have to sneak out in the dead of night if you can't get some type of waiver. CBP used to have a web page up with particulars but I couldn't find it.