As a administrator you can roll a person forward from last season into the new season.
To do this go into Dashboard, Online Registrations, click on the name of last seasons registration form, then click the roll forward icon beside the persons name.
This will open the new seasons form, prefilled with last years details. Simply update any details and click Submit. They will then appear in the new seasons registration form and when you view last seasons database they will be highlighted in green.