If the original work, for reprint, needs updating and it is preferred that new material be included within the original work, the copyright release being sought should indicate updating is expected or acceptable. Once the groundwork has been laid, decisions as to whether to insert new pages, leaving original pages untouched (except perhaps for renumbering), or updating an electronic copy should be made. Even if open ended, unlimited  copyright release is given, it is never recommended original material be altered – much like cropping a photo for publication should not involve scissors on the original photo or negative. Technology has advanced sufficiently that original material never need be destroyed.

Taken from