I'd remove every leaf that looks droopy and sick, even it it means giving your plant a total haircut. Those leaves will likely turn black/brown. Given proper care, your plant will put out plenty of new growth from the crown.

I agree with Rhizo. Marred leaves will not revert to green. No matter what you do.
In the meantime, remove all frost-bitten leaves. Place in a warmer, medium light spot.
Do not fertilize.
There's a product called Superthrive. It's a hormone and contains 50 vitamins. Buy a bottle. It's not fertilizer.
I normally use 4 drops per gallon of water, but stressed plants should get 10 drops per gallon.

Once new growth sprouts, add half-strength, balanced fertilizer. Good luck, Toni