[Answered ]-Django JSONField

What you want to do is a data migration.

1. Keep the existing jsonfield and add the new PostreSQL JSONField.
2. Generate a data migration, which iterates through each record migrating the data from the old field to the new one.
3. Once you’ve run the migration you can deprecate the old field and remove it without any data loss.

References

Django Data Migrations

yes you can change fields’ types and names without loosing the data.
You just need to run makemigrations and migrate every time you change something`in your models.py