Barely feeling the effects of MDMA after heavy abuse

Tried the crystal form of MDMA for the first time when I was 15, and the experience was completely out of body and euphoric, It honestly helped a lot with my mood as I was going through a depressive period. After that I began rolling every second week which then turned into every weekend for about a month, id say I rolled 25-30 times in 3 months. Upon turning 16, the comedowns began to not even be worth the roll as the effects became weaker every ping. Abusing crystal form of MDMA for 2-3 months will deteriorate the effects at a quick rate. How long should I let my serotonin receptors repair themselves and heal from the abuse before I roll again?