The only true way to get accuracy is to have the pitcher throw pitches, pitches and more pitches. She has to throw 100 to 150 pitches every night, PERIOD!! If she is not willing to sacrifice this time and effort, find another pitcher. Enough said here!!
Ok that was a bit harsh. I use an inflatible toy in pitching practice a lot. The one I use is an inflatible Mickey Mouse. It is the kind with sand in the bottom of it so it stays upright. If the ball hits it (which with young players is often) the ball drops straight down and does not deflect to the catcher (me). I set Mickey in the batters box and call for inside drop balls (peel drop) and inside fastballs.
It works Great!! There is one drawback. Every now and then, the pitchers hit Mickey on purpose. You can count on replacing Mickey about twice a season, but at about $5.00, it is a great tool!