Usually, when potted lilies are either too wet or too dry, the leaves will turn yellow and fall quite rapidly. After Eights seem to be real sensitive about being too wet(for me anyway). I would suggest putting the plant in a semi shaded spot where it is a little cooler and keep it just barely moist. With lilies, being a little drier is always better than being too wet. Keep the stem and leaves just as they are and then plant it out in the garden this fall. Since this lily was 'forced' to flower early in a nursery greenhouse, some loss of leaves after flowering is not all that unusual. while the plant adjusts to the outside world. It won't grow anymore new leaves from the main stem(s) this year, but don't be surprised if you see new little baby plants come up--After Eights multiple pretty fast!