By default you can create a separate long term plan for each term. You can also edit the timeframe for a long term plan to cover multiple terms.
1. Open your long term plan and click on the text at the top left hand corner that displays the Title, Term, and Collaborators. This will open the plan edit screen.
2. In the plan edit screen change the Last Term to extend the time-frame then click Save.
3. You will then be able to start creating blocks for future terms while still being able to view your original plan.