Changing your personal statement should be a fairly simple thing. At this point, I can't imagine going to all the work of getting new letters; your letter writers for neurosurg can attest to your general abilities, and I think most programs understand that applicants do change their minds, even during the application process (even if it's such a minor change, as from neurosurg to general). If programs have questions, this is something you can clarify further in interviews; I doubt a progam would deny an interview simply based on a letter that seems more geared to neurosurg than gen surg.
