How many were built during the war, and did production continue in peacetime ? There must be a few left to refit...
IFM established that 15 or 16 NX-class vessels had been built in total. Though not compatible with the novel continuity, Star Trek: Legacy
had the Currie
(NX-16) and the Avenger
Btw, the Terran Empire also had a couple of NX-class ships.
Edit: The Enterprise
underwent a severe refit in the previous ENT novel. It doesn't refer to the Drexler refit but it would fit. I pictured the NX1.5 for the rest of the novel. Btw, the Intrepid
(NX-07) was specifically not refitted in IFM.