A good one is: "(I'm) glad to hear you're better." You almost got it yourself.

I agree with Michael, "I'm glad to hear you got better." The formal word for "getting better from sickness" is "recovery." "I'm glad to hear you've recovered from your surgery." "So-and-so has made a full recovery from his rotator-cuff injury." "How long does it take to recover from a sprained ankle?"