Lemmings, I am not familiar with the add on, and this may be a question for the developer.

Is there a restore data option?

However if you open up the profile folder Profiles - Where Firefox stores your bookmarks, passwords and other user data does this add on have its own folder where this data might be stored?

Maybe try to add the data file to a new profile first to make sure that the restore is full proof. First find where the json file should live and make a copy. Create a new profile, and install the add on. Open that folder for the new profile and copy the json file into the place it used to live and start firefox.

I don't see a separate folder for Lightbeam in the Profiles folder . When "Save Data" is selected in Lightbeam, it creates a .json file in my selected download location. The file is named "lightbeanData.json" and this is the only location of this file. . I have noted in a separate question that in addition to the "save file" issue, now there is no scrollbar button in list view, so I can't scroll to other information in Lightbeam other than what is shown on the screen. I have removed the Lightbeam add-on, reset Firefox, and selected "Lightbeam" as an add-on, reinstalling Lightbeam. The problem persists and I still need to know how to restore Lightbeam data.