How do I keep Facebook likes after URL change?

Hi all

I’m working on a site that needs expanding and one of the url’s needs the file extension removing .php so I can page/extra-content and so on…
My problem is this page has a good amount of likes but once I remove the extension everything is back to zero. (100 likes)
to (0 likes)

Is there a way to keep the likes after I’ve removed the extension?