Watering potted plants is easy, but getting the whole root ball wet is hard. When you let the root ball dry out it shrinks away from the inner walls of the pot. If you pour on water, it goes straight down this gap and out the drain hole. The best way to rehydrate a plant in peat based potting soils wets the entire root ball, encouraging roots to travel into the center.
You can do it on the kitchen counter by filling a shallow container with a few inches of lukewarm water. Then set the potted plant right into the water. Let it sit until the surface of the potting soil is visibly wet. It may take at least an hour, then remove it to drain in the sink before returning to its place. Do this whenever a plant (indoor or out) has become overly dry to give the peat time to rehydrate completely.