Rusty, you don't say how old your daughter is. Or how fast she throws the 9lb ball. Your best bet is to discuss this matter with a youth coach and
Pro Shop person, so they can see her bowl and determine if she's able to handle a fingertip ball of more weight.
Rusty, if you yourself bowl, then you know how sporadic scoring can be. You can go on an abosolute tear for weeks, then come back to earth with more average scores. It sounds like your daughter is doing great and enjoying the game, but I'd get someone to actually watch her before determining a ball upgrade.
Erin