I memorized half of the Quran when I was about 13 years, now I only remember up to 1 juus and not even the whole juus but like 6,7 surahs
If you don't keep up, Quran will disappear from your heart. But on the other hand if you start repeating again, it's easier for you to memorize everything! Are you thinking about starting to memorize again? Haven't you been reading those surahs during prayer?