I am sorry you're going through this. I cannot speak to having two surgeries for cysts. Are they sure it's a dermoid cyst? Imaging is not exact so they oftentimes cannot be sure of the type of cyst. For instance, what is thought to be a dermoid cyst could be hemorrhagic or endometrioma. Typically, the "standard" is to monitor via periodic ultrasounds. If the cyst doesn't resolve and gets over 7cm or so then surgery would be the next step.
If you do end up having surgery, you will want to make sure the consent form states that only the cyst can be removed and not the ovary. Many women come out of surgery missing an ovary or ovaries for benign cysts. We need both our ovaries, uterus and tubes our whole lives for good health and well-being. Yet, hysterectomy and oophorectomy are two of the top overused surgeries.
I hope this helps!