You don't "refurbish" an atomic trigger. It's not a mechanical part. It's a radioactive element that decays rapidly. That decay, however, also means that it doesn't last very long before it becomes material that is non-useful to reactions. You can replace triggers, but you don't "refurbish" them because there aren't any parts to fix. You simply need new material every 90 days or so.
I was actually referring to refurbishing the entire bomb.
This would include replacing any parts which have expired due to nuclear decay, any damaged by the radiation environment, and any which are unreliable just due to age.
My point was & still is, that even with an expired nuke you still have known good fissile material and a known good design. Making one of these workable again is much easier that starting from scratch.
The other noteworthy aspect is that it may be possible to trade some of the non-working devices to a nation seeking nuclear capability in return for technical assistance with the remaining ones. This gets around the notion of bringing a horde of barbarian warriors up to the technical level necessary to maintain a nuke.
The nation make choose to rebuild them or extract the fissile material and make a larger weapon of its own design.