Is it necessary to re-memorize parts of the Qur’an that were memorized out of showing off, after repentance?

We advise you to continue memorizing the Holy Quran while striving against your self (nafs) to achieve sincerity and repel showing off (riya'). Do not re-memorize what you have already memorized. Know that a believer holds himself accountable and fears showing off, but he is moderate in his self-accounting and does not go to extremes in it. For indeed, that may lead to despair and despondency and the abandonment of good deeds, and this is from the deception of Satan.