We license on the URL, not the domain. The Test URL is a permanent URL once set, unless as previously mentioned, you change the domain on the Live URL. That is the only case which we would reset the Test URL.
If you would like to take advantage of the courtesy reset I am offering, we would require the new Test URL, yes. I would recommend using a sub-domain of your Live URL's domain, however. As this would give you the most flexibility.