Make prior (registration) webinar recurring

HELP-Urgent! We held a by-registration webinar today and have another session tomorrow. We advertised ONE link for both days, but somehow the recurring meeting setting did not work. We desperately need the people who registered for Day #1 to be able to use the same link that was in their original registration confirmation email for tomorrow's webinar session. Can I change the settings in the original webinar so this can happen? Praying someone can help me as there are 500 people!