I think a phased approach is your best option. What's missing from Cvent is being able to send emails to those who haven't registered for any sessions, i.e. someone that didn't pick ANY, indicating they haven't come back to registration. Maybe offer an incentive of sorts for completing their sessions? Depending on how big your conference is, you registration team can review their agenda with them upon check in?
Sometimes long registration lead times hurt in the end - maybe sending out a save the date email to your potential registrants and then tightening up the registration window might also be an option.
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Beth Vriesen
Events Registration Admin
Associated Bank Corporation
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