I have tried this and was really surprised as to how well it worked. I put the milk (used 2%, and not sure it matters) into a small sauce pan (enough to cover the ball of Mozz), added salt and then brought it to about 105 degrees. Took it off the heat and let it cool down. After about 1-2 hours, it would have been very difficult to tell it apart from a ball of Mozz that I had just made fresh. I would add that once I left it unattended on the stovetop and it quickly turns to mush, so you need to be mindful and keep an eye on it.
This was a real revelation and provided some liberation if I wanted to serve fresh Mozzarella to company but did not want the pressure of making it shortly before they arrived. Very much worth trying.