Steps to Migrate in-flight data:
* Go to Process Admin
* Click on Installed Apps
*Click on the snapshot you want to migrate instances to
* Now, on the right side panel, you can see Migrate in-flight data.
* Click on Migrate in-flight data.
* It will list down all the available snapshot version from where you can migrate instances.
* Select the snapshot version
* Click Migrate.
Depending on your implementation there can be various considerations one of the important is: if you have orphan tokens, you may consider writing policy to move them.