Pour 1 cup of apple juice into a microwave-safe bowl or large measuring cup. Microwave for about 90 seconds, until it’s very hot and near-boiling.
Add the strawberry gelatin mix to the hot juice and whisk until dissolved.
Add the remaining juice and whisk to incorporate.
Pour the mixture into a Ninja Creami pint container, being careful not to exceed the max fill line, and close the lid.
Remove the pint from the machine and check the consistency.
If it appears crumbly, scrape down any icy patches on the inside wall of the container, then insert the pint back into the machine.