Since v1.4.4 you can create a backup file and restore data from the backup.
You can also transfer data by uploading the backup file on a cloud storage, such as iCloud and Dropbox, and downloading it to the new device.
https://www.youtube.com/watch?v=iFk4WLxQzQs* We are currently developing our original cloud service for Planner app.
* To transfer the items that you bought at the stationery store, you need a Planner account which you can create/sign in on the purchase history page.