how to replace the part in tooling split

Recently I have made a mold using the standard moldtools-PARTING line ,Shut Off surface,tooling split .. etc.But afterI finished all drawings,customer sent a new part file.
WHAT IS THE FESTEST WAY TO REPLACE ALD WITH NEW PART,WITHOUT TO DOALL SPLITING PROCCESSS FRO THE BEGINNIG.

Thanks,

KostadinSolidworksGeneral