In the Curriculum Engine, if you have exported a calendar layer's information into an iCalendar file (Help Topic: Exporting Calendar Layers), you can import that file back in to the Curriculum Engine as a new layer.
Click on the button below the calendar.
Click on the button to display the "Import Calendar Layer Archive" overlay.
Select the file to import by clicking on the button (Firefox/Internet Explorer) or the button (Chrome/Safari).
Click on the button to upload the file.
After the file has been uploaded and processed on the server (which may take a few minutes depending on your file's size), an overlay will appear detailing the results (e.g., the name of the newly uploaded/created calendar layer and the number of new items on that layer).