Heat does not provide api/cli to migrate the given template from old heat version to later.
Heat is being released inline with each Openstack release and there is a chance that resource properties and attributes might have changed and/or deprecated across these releases. A user may wish to migrate the template to current version which was created during earlier version say juno. Currently heat does not support it.
Heat already having mechanism to define the translation rule for each of the properties being deprecated by using translation.TranslationRule. This is being implemented in resource plugins in order to support migration to new property in place of deprecated one.
This feature could be updated with below command
openstack orchestration template migrate -t <template-file> --output-format [json|yaml] --output-file <output-file>
This command will migrate the given template file and will write the template output mentioned in output-format.
Command will provide messages of changes made to the deprecated properties in below format:
<resource-path> <property> <action> <details>