Currently, JFBConnect will only post an article one time, and it would only be when the article is first published.
In order to re-post content, the best suggestion is to do it from the front-end of your site with the "Create Post" button in the social toolbar JFBConnect adds for admins on the site.
The other option would be to remove the history of that post in the Admin -> JFBConnect -> Channels -> History section. Then, unpublish and republish the post and JFBConnect will re-submit it.
We haven't had a request for reposting content, but I can see the value of doing it. We're in the planning stages to update and improve the channels area with new features and support for more networks. We'll see if there's some things we can do to make reposting content simpler as well.