Maybe you've already done this, but you could try putting something on or around the plants your cat likes.
Granted, a lot of orchids don't like stuff on their leaves, not even water. I was thinking a solution of Neem oil, as the stuff smells funky but I'm not sure if an orchid would or wouldn't mind that or if it would deter a cat.
If all else fails, you could try dabbing some castor oil on the pots and hope your cat is dumb enough to lick it, lol.
EDIT: actually nevermind. Castor oil is potentially bad for cats. Maybe try a little hot sauce on the outside of the pots, I have no idea.