I read an article/abstract I found on pubmed addressing this question exactly. The conclusion was that in the absence of any symptoms indicating a new disease is present, there is NO reason to repeat the work-up of an idiopathic neuropathy. In terms of repeating the nerve studies themselves, this wasn't addressed, as it was about idiopathic. For that, the answer is it's not necessary unless something really changes.

But repeating tests did not reveal any new diagnoses over time, as I recollect.

Gads my humor is gone. Or something else, cause it did not cross my mind. Until you guys put it there!