The best approach is probably to cut off the spent flowers once they fade and keep the plant in as much direct sun as possible (indoors while the temperatures are cold, then outdoors if the plant still has leaves by early spring). This will keep the bulbs "fed" while the foliage photosynthesizes, though at some point, like outdoor-grown bulbs, they will go dormant and shed the foliage. They can then be stored until the typical planting season of early fall. As Iowa State University's brief article about this topic says, though, tulips in particular might not fare well with this treatment simply because they tend to be short-lived plants in our region anyway, even if grown outdoors. There's no harm in trying of course, but the plants might not bloom again if they spend next winter in the ground. (Daffodils, hyacinths, and others can live for many years in garden beds, but tulips usually need to be planted fresh each year.)

Miri