"What you are doing is playing, not practice. When you play through a piece like that, you spend most of your time on the bits you already know, and just a little time on the parts you find difficult, and you end up not repeating the hard parts very often. To practice, you should stop when you find something difficult, and repeat that part until you can do it well, and then move on to the next."
You will improve through simple repetition (edit: of a whole piece, or anything else where you know large parts of it well), but you will waste a lot of that time cementing things you already know very well.
And this is what marks the difference between time spent "executing" work in an area and practice in an area. Reaching the top in most areas will for most people mean shifting the balance between amount of time worked in that area and the amount of time spent on deliberate practice towards more deliberate practice and less towards performing.