I haven't had that problem with my key. Try replacing the battery in the key. I replaced the battery last year. Libby was parked outside, I was in the master bedroom and I armed it. Signal went through four walls to get to the libby.
If you dropped the key in water, take it apart and dry it. replace the battery.
I have heard a dealer replaced key is over $200 + $90 reprogramming fee.... never had a problem with my key so I never confirmed those figures.
walmart sells the key (remote).