Did you modify the workflow installed with the plugin or did you create your own workflow and attach it to the catalog item?
If it’s the latter, you should just have to create an update set and update the catalog item to use your custom workflow.
If that doesn’t work, I’ve also just completely uninstalled the plugin and reinstalled it to make sure everything gets updated. All the sys_ids for the catalog item, widgets, etc. are still the same so it’s not a big deal