When it comes to increasing speed I would be careful to make sure your dd's efforts are not being sabotaged by the above quoted instruction you are receiving. The pull down, snap at the bottom with a perfectly timed wrist snap at a perfect "release point", finish straight up with a bent arm can result in lots of frustration caused by well meaning instructors and parents. I've been there in the past. It is likely the harder she tries to throw like this the higher it will go.
Please read this link on the topic of internal rotation. See if this is the outcome of the instruction your daughter is currently receiving. If she can get this idea of "throwing" underhand at age 10 you will be well on your way.
Imagine throwing overhand by always having your hand behind the ball and your forearm facing the target and pushing forward relying on a perfectly timed wrist snap to throw hard (of course this is not how we throw overhand) as opposed to rotating your shoulder and forearm to realease to throw hard. Method 2 is how we throw hard overhand. The same applies to throwing underhand.
I've coached a bunch of local kids over the past 10 years as my daughters have moved through. This last batch of pitchers (9 and 10U) is turning out the best by far (at least relative to their age)because of my recent understanding of how to throw the ball underhand using internal rotation which has no relationship to most instruction and printed materials on the subject of pitching.
They used to tease me at the academy for saying the same thing.
