When taking a will to probate.. do the original witnesses of the will have to resign to the fact that they witnessed the will after the person is

No, you don't need to have the witnesses re-sign.  The fact that there were two witnesses allows the will to be self-authenticating (meaning you don't need to prove that it is indeed the decedent's signature).  That's really the only reason for the witnesses.  If there is a challenge to the will, it might be necessary to locate either the witnesses or the attorney who prepared it (or the notary),  as it is usually done at the attorney's office or in the presence of a notary.