Look closely at the Carbon Express Medallion XR 2000 series.
Very durable, but not inexpensive. Can be hard to find.
Plugging some numbers in On Target II software, if the bow can be shot at ACTUAL measured 24# draw weight, the XR 2000 can be cut to 28" in length and use a 100gr field point and will have balanced spine.
This will give her room to grow, without having to completely change arrows every draw length or poundage increase. As poundage or draw length increases the shafts can be cut a little shorter to increase spine, and/or add tip weight. Just use hot-melt glue on inserts. Not superglue!
A half-dozen can last a long time. One can always cut shorter to strengthen spine, can never add length once cut.
I recommend 100gr field point weight simply because they are so common and cheapest in most cases. I recommend carbon shafts for their durability.
Carbon Impact Super Clubs 20/30 are an alternative when you can find them. Lancaster Archery may be of help. Link is attached below.
There just are not many good choices for youth when most arrow manufacturers push overspined 500/600 arrows which often do not result in the best performance. http://www.lancasterarchery.com/carbon-impact-super-club-arrow.html#fullDescription