Hindu law does not apply to a person who is a Hindu by

Hindu law applies to every Hindu, however that status was acquired. Section 2(1) of the Hindu Marriage Act, 1955 covers "any person who is a Hindu by religion in any of its forms or developments", and courts have long held that a convert to Hinduism, and a person who re-converts to it, is a Hindu to whom Hindu law applies.

So Hindu law applies alike to a Hindu by birth, by conversion and by re-conversion, and none of the given modes takes a person outside it.