In the GoToWebinar dashboard for that webinar (gotowebinar.com), go into the Registration section and see if you can raise the registration limit. If you have an account that allows you to have 1,000 Participants in a webinar, you should be able to raise the Registration Limit to 10,000.
You should not have to move Registrants to a new webinar in order to access your new limit.
Fantastic - thank you for putting my mind at rest. As the webinar was created before we upgraded, I was worried in case anything may have happened to this session that may cause issues on the day.
Many thanks again