The most common cause of leaf drop is inadequate watering, but it is usually accompanied by other symptoms that can help you decide whether you need to use more or less moisture. For instance, if the foliage is yellow and the potting mix wet, you should reduce the watering frequency. And if the leaves are drooping and turning brown and crispy, you should irrigate your plant. Your peperomia can also drop leaves if you’ve just repotted it, as it goes through transplant shock (which is normal, so just give it time), or because you’ve changed its location. Sudden temperature changes can stress out the plant, so make sure to avoid it.