Hello Bob,
Thanks for writing in!
To Revoke your License and assign to a new site please do the following:
1] Please go to X Addons > Home and revoke the validation.
2] Please login to your account and revoke the license. https://community.theme.co/my-account/
3] After you have revoke the license, you need to re assign the license again to your site using this url: https://www.your-domain.com/. You have to make sure that url you just assign is the same as the one you have in your settings, Settings > General > Site Address
4] Go back to X Addons > Home again, and insert the license again.
Hope this helps.
Joao