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I don't believe so. The Apple Watch doesn't have a physical port that you can access (like the iPhone does). You can, however, take it to an Apple store and see if they can do it. I'm pretty sure there's a hidden port in the watch that only Apple technicians can access. I don't know if they'll reinstall watchOS just because you ask them to without a reason, but it'll never hurt to try.
 
not sure why you want to do this, (an explanation of your problem could help us direct you in the way to go)
but an unpair and re-pair tends to clear up a lot of problems.

With the re-pair you can restore from backup, and most of the time the problems will sort themselves out.
 
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