You could repot the plant, which is what I would do. The reason is that I would want to know what kind of potting mix the plant is growing in, rather than let it remain in the unknown mix which came from the store. Sometimes I also feel the mix they provide is some cheap mix, just enough to get the plant on the shelves and into someone's ownership, where the eventual death of the plant could be from many reasons, but the owner will sometimes think it is because they didn't know how to take care of it.

The conditions you described could have several causes. In general, make sure it has enough lighting and don't overwater or underwater.