Sounds like she is in Breech of Contract if she is not abiding by the signed and notorized agreement you had. You could sue her for breech if that is the case.
If my understanding is correct…and YOU stayed in the house at separation time (and she left), then any improvements made after the date of separation wouldn’t be included in the increase of value. I MAY BE WRONG, but my understanding is that the equity at the time of the separation is what is based on the equitable distribution. Her interest in the house only includes the time that she lived there. Hopefully the lawyer or someone else will correct me if I’m wrong [:)]
The only way to end the agreement is by mutual decision. She would have to go to court to have any changes made. She is bound by the agreement she signed and if she’s not doing something she’s supposed to via the agreement, then she is in breech and can be sued by you.