You can puree some of the potato in some broth and add it back to the soup. You can alsouse some flour in cold water and stir that into the soup to thicken it. Corn starch/flour works but if you cook the soup after adding it or reheat it the next day, it will lose its thickening power.
"If you want to make an apple pie from scratch, you must first create the universe." -Carl Sagan