How can you add new most visited website to the google chorme new tab page?

I recently had Facebook on the most visited section of the new tab on Google Chrome. But the thumbnail pictures for it were of a profile I was looking at. I wanted it to show my profile so I decided to press the "x" on at the top right of the thumbnail then hoping to just go back to the site and it would appear again. But apparently it completely blocked it and will not reappear now. So what do I do to get the Facebook thumbnail back onto the most visited part on the new tab?