Is it permissible for a pilgrim in the state of ihram to exit from a Umrah without shaving his head, and to suffice with a previous shaving for a recent Umrah?

He who performed Umrah, then shaved, then exited ihram, then performed Umrah again and no hair grew on him, is not required to pass a razor over his head, and exits ihram without any obligation upon him. However, if hair grew, even if only a little, he must pass a razor over it. If he does not, he remains in his state of ihram and must strip off sewn garments and shave or shorten his hair to exit ihram.