There is migration script https://github.com/redhat-developer/codeready-workspaces-deprecated/blob/6.19.x/operator-installer/migrate_1.1_to_1.2.sh which should work offline.
We need to test it carefully.
https://codeready-workspaces-jenkins.rhev-ci-vms.eng.rdu2.redhat.com/job/pre-release-offline-migration-testing-against-OKD/