Is it obligatory to review what has been forgotten from the Noble Qur’an, and what was memorized without the intention of memorization then forgotten, and in case of doubt regarding the intention of memorization?

Whoever forgets the Qur'an due to negligence is disobedient to Allah Almighty, and must hasten to repent. Part of completing his repentance is to review what he memorized, if possible, whether his memorization was through learning or through repeated reading. Whoever doubts having memorized something is not obligated to do anything.