Undertaking regarding my children ending, what do I do?

[Woodstock21]

Hi, hoping someone can help, after a long civil family court case my ex husband was stopped from ANY direct contact with my children (all under 18). Any contact including supervised, phone calls, social media etc. Was denied by the judge. He is entitled to letterbox contact via a P.O. Box 4 times a year. The judge was so concerned about his behaviour that he was made to sign an undertaking in respect of the children - not to come within 100m of them, their home or encourage anyone else’s to etc. The judge made it clear that they would issue a non mol in respect of the children if he didn’t . my question is the undertaking is due to run out very soon (it was for 12 months) , my ex is still very much around and is ensuring I know about it. Will he need to do something in order for the court to get hi to sign another. What protection do my children have after it ends?