In the past I had kept the no-ip software running on the computer, and it would auto-update in a situation like this. So we'd just need you to make the change.
But it's been so long since there was a problem I stopped running it, I wasn't even sure if it was needed anymore. I guess I got my answer.
I now see that there is a new feature in the firewall software. I can give it the dynamic dns address and it will check every 10 minutes for the ip and if the ip changes, it will allow it.
If it works like it should, then an IP change shouldn't block the request system more than 10 mintues.