Some individuals discard the amaryllis after flowering. Others keep the plant from year to year. In order to bloom again, the amaryllis needs proper care in fall. 
Plants that are outdoors should be brought indoors in mid-September. In order to bloom, amaryllis bulbs must be exposed to temperatures of 50 to 55 degrees F for a minimum of 8 to 10 weeks. This can be accomplished by inducing the plants to go dormant and then storing the dormant bulbs at a temperature of 50 to 55 degrees F. To induce dormancy, place the plants in a cool, semi-dark location in late September and withhold water. Cut off the foliage when the leaves turn brown. Then place the dormant bulbs in a 50 to 55 degrees F location for at least 8 to 10 weeks. After the cool requirement has been met, start the growth cycle again by watering the bulbs and placing them in a well-lighted, 70 to 75 degrees F location. Keep the potting soil moist, but not wet, until growth appears. The other option is to place the plants in a well-lighted, 50 to 55 degrees F location in fall. Maintain the amaryllises as green plants from fall to mid-winter. After the cool requirement has been met, move the plants to a warmer (70 to 75 degrees F) location.