Here’s how to force Facebook to refresh their share cache
The Issue: When posting a link on Facebook, sometimes you may see the image, title and/or description as it will be posted, and want to make a change within your content. Given the standard posting process, that page information has now already been cached and can’t be updated. This means that even if you try posting in a different place in Facebook, in a different browser, on a different computer, or even after waiting a few days, it is going to pull the exact same information from their caching system that it pulled the first time.
Side Note: It makes complete sense why they would do this…to save systematic overhead not having to ping content source servers each time the same link is posted.
The Solution: Facebook has a debugger tool for developers that takes care of this issue and allows you to refresh the share cache information for a specific URL. You can find it here: https://developers.facebook.com/tools/debug/