Cut or snap off the old bloom stalks near the base, keep them watered and wait for the new bloom scapes to appear. If some of the leaves are looking ratty you can pull them off.
FYI Stellas are daylilies (hemerocallis) not true liles (lilium)

I shear the whole plant down to about 4 inches. They start regrowing just like its spring again. Leaves are dark green and healthy and blooms beautifully. This is easier for me than constant deadheading and the plant looks happier.

Interesting idea crosscut, though I'm not sure it would work as well in my short season zone 4 garden. I may just try it with one plant to see what happens. Mine are about half-way through the first bloom cycle right now, a bit late this year.