You can just continue on, with no problems. The year start/end dates is used with the reports – you can select things like “Current School Year” and “Last School Year”…
So lets say you did 15 chapters of a 20 chapter book this last year. You don’t make any changes to things in the scheduler, and this current year you read the last 5 chapters. The report for last year will have something like
This Great Book ch1-15
and this year would have something like
This Great Book ch16-20