Is it permissible for someone intending 'Umrah to shave their head completely with the intention of repeating 'Umrah, knowing that they might not have hair to shave for the second 'Umrah?

If a pilgrim performing 'Umrah intends to repeat it, he may shorten his hair in the first 'Umrah to leave some for subsequent 'Umrahs, as shortening is sufficient, even if shaving is preferable. If he shaves his head, he may wait for his hair to grow back before performing 'Umrah again, or he may perform it before that, which is permissible.