Unfortunately, no, you can't retrieve them. Almost all social buttons (Like, Google +1, etc) are based off of the exact URL of the page they are on or reference. If the URL changes, the Facebook will think that it's a new page.
Within the JFBCLike button, you can set a specific URL that the Like is for. So, technically, you can have the Like button show the Likes from the old page. The problem with this is that the old URL is what will then be used in Wall posts and other areas that the Like is posted to. So, you'd want to make sure a redirection from the old page is setup if you do this.
Hope that makes sense. If you need help using the href parameter for the Like buttons, we can help. However, unless you have lots of Likes, you may just be better starting over on most pages.
Alex
Liked articles vanished - not temporarily
