Where are you located? If your weather's been really hot, it might need a vacation in a shadier place. Especially keep it out of the hot afternoon sun.
These are shrubs that grow along stream beds and such places, that usually have tons of water, and dappled shade. IF it's cooking in the sun these days, it may not be able to suck down water fast enough to keep its new leaves growing.
Also, is the pot a dark color? That might be heating up the root ball when the sun hits a dark pot, too.