What you described about Sunday school homework and having to sit down with her and redirect her attention back is more in line with what you will probably be doing for a while. Habits are not formed over night. They are habits because we are consistent in our approach.
Also, do you make her do the incorrect problems over? My DD9 really woke up last year when all of her papers came home and I made her redo those she missed. This was a great opportunity to go through material to see if she really understood it as well as a great incentive for her to pay more attention to what she was doing. It was also a great time to reinforce the belief that it's easier to do it right the first time.
I don't know if this will help any in your DD's case but it worked well for us.
