I had laparoscopic surgery last 2013 to remove cysts on both ovaries. After that I was given GNRH for 3 months and has been on contraceptive pills since then. My recent ultrasound revealed that the cyst on my right is back (and is about 6cm) while my left ovaries remain normal. Does this mean I have to undergo another surgery or can hormonal therapy still help at this point?

This means that you have to discuss this in detail with the doctor you trust.
Are you just waiting to see her or him, after the ultrasound?
If you don't have a regular GYN, it's time to find one.