@magdo,
Muslims read the Koran again and again to keep to memorizing it and not to forget it; this is for those who know it by heart. Or they try to contemplate and understand its meanings and assimilate its aims and legislations to use it in their practical lives, and this is for all Muslims. They also do this for easing the soul, purifying the heart and clearing the chest, it is as God says:
"Say: "It is a Guide and a Healing to those who believe," Surat Fosselat, verse 44.
God shows in another verse the type of this cure, he says:
"And a healing for the (diseases) in your hearts," Surat Yunos, verse 57.