Best way to clean lace curtains to keep them "crisp" instead of limp ?

Have you tried oxy clean!? Lol n otherwise I believe starch should work!

https://www.doityourself.com/stry/how-to-clean-lace-curtains

Also available spray on starch and an iron

Avoid fabric softener when you wash them, too.

I would use a good spray starch and a hot iron.

Iron the curtains with spray starch, and the border lace twice. Let them dry completely before hanging. ☺️

I'd be afraid to use starch, but what I do with mine is to use a liquid softener in the rinse, & hang mine back up right out of the washer. I give the bottoms a gentle tug & kind of give them pinch pleats by pinching them & they hang-dry kind of stiff & look nice.