>>6
As I already said, you should just stop doing it. I'm not saying it would be very easy, but it won't be particularly hard.
I think your problem is a combination of the two:
1. A bad habit.
2. Thinking about other things while reading.
To fix #2 you don't have to do anything special, just manually block other unrelated thought. Try it out right now: stop all thinking and listen to silence in your head without reflecting upon anything. Thoughts will occure spontaneously, and you can't do anything about it, but you can elect to not prolong them and let them pass by, which is a trivial to do. You sit down and listen to nothing, and when you think, "there's 4chan in my browser," you don't start thinking whether you should refresh the page or click a board, you just let it all go. "I wonder if there's something funny going on /v/," you think, and let it pass. "I wonder what time it is," but don't look at the clock and don't bother thinking why you should or shouldn't look at the clock at all. Let it pass. THAT'S exactly how a reader's head more or less looks like while he's reading a book, concerning everything except the material in the book itself. If you're going to read normally, you simply have all other thoughts on stand-by. This is easier than it sounds, it's just that talking about simplest stuff is always the hardest. You can't count and recite a poem at the same time, you can't read while you're thinking about what happened earlier today and what cool things to do in next weekend.
#1, like all bad habits, is harder to fix. You just have to stop yourself manually whenever you can, until it disappears. Don't let yourself re-read sentences at all, even if you completely forget what you just read. Punish yourself with ignorance every time you try to forget and re-read something, and your habit will vaporize soon, maybe after a few days or a week's time max.