Ren here from the Shopify support team, thanks for your question!
At this time, there is no automated way to transfer your Print on Demand data from one app to another. You'll essentially be starting from scratch to create your Print on Demand products as the products have to individually sync up to allow the order information to send to your warehouser and allow them to fulfill the order accordingly.
An option you do have would be to hire a Shopify Expert to assist you in transitioning all of your products over if this is not a task you want to do on your own. Check out our Expert Marketplace where you can post a job to allow experts and developers to offer proposal on the description you provide.
That being said, our support is also available to help you through the process so if there is any part of it you'd like clarification on, or you have questions about getting started don't hesitate to ask!
What's prompted you to want to make the switch?