Film about a boy, a dog, a frozen lake and a car crash.

I watched this film quite a few years ago but I cant remember the name. From what i can remember, it involved a boy being surprised with a puppy at christmas. He then hides his firefighter dads keys so he doesn’t go to work, meaning that the mother drives him instead. They end up in a car crash and die. I believe that there is also a scene with a child falling through a frozen lake. The boy and his dog then change the past, i believe, so that everyone survives. Any ideas?