my first suggestion- start saving money,90% of captive female iguanas end u needing an emergency spay due to becoming egg bound- which is fatal if it happens without having the eggs removed through surgery.
2nd suggestion- do you have a digging box for nesting/laying?
3rd- If she is in a cage with another iguana she may not be comfortable laying.
4th Bath daily.
5th-allow her lots of time to roam around and exercise. this allows the eggs to move down and builds muscle for easier laying.