I've talked to various people about the issue you brought up. (I am in the same boat.) Some people have told me that insurance companies don't want to insure us, former IVF patients, because (1)we might do IVF again and thus ask them to cover the expense or a part of the expense of IVF drugs and (2) we might have a disease or condition, such as endometriosis, PCOS, etc. which led to us doing IVF that might indicate that we might have medical problems that need to be treated and thus ask them to cover the expense of treatment. Even though you and I do not want more kids and even though we don't have these types of medical problems--I naturally conceived my second child after conceiving my first through ICSI, the insurance companies categorically turn down groups of people even though some the circumstances/profiles of some individuals in the group "should" be considered mitigating circumstances. I cannot verify my relatives and friends' assertions, though, as I do not work in the health insurance industry. I highly suspect what they say is true.
Please let me know what you find out.