I don't see why you would go back to revision 0 if you already have the documents in place. If your documents need revision prior to your new audit, you would assign a new revision number with updated date of edit. For documents where processes haven't changed, you should still put in a review date for your recent review, as you should be reviewing procedures annually for updates. If you have documents that are new to the current BRC issue, then you would start with Revision 0.
Also, if your procedures include a BRC clause reference, be sure that the reference in your previously made documents matches the clause for the current BRC revision.