If your girl is ready to lay she will become restless and will often dig at the bottom of her enclosure and she may stop eating altogether or eat less. It would be beneficial for you to place a large laying bin in her enclosure which is at least 12 inches deep with a damp soil/sand mixture. It has to be damp enough that a tunnel can be dug without having it fall in on her! You can route a vine I to it so she has a way in/out. Give her complete privacy and yes, cover the outside of her enclosure with a towel (I use brown parcel packaging - it's not to thick and doesn't hinder air flow into her cage). Then leave her alone but quietly check on her every now and then.
If your girl does have eggs but is having a hard time laying them an x-ray can determine if she has any and if she's be one egg bound. There is a drug vets administer to help induce laying - this would probably be done before a 'chameleon c-section' but don't wait too long to find resolution with this problem. If she doesn't lay and she is displaying signs that she needs to, get her to a vet! Good luck!