You posted this somewhere else -- the photo isn't viewable by the public, which is probably why you didn't get many responses. Just thought you'd like to know.
The Riedell 21's are the Blue Ribbon model. If she's doing freeskate elements (spins, single revolution jumps), it's probably time to upgrade to a new skate model, regardless of the fit.
Boots really don't last forever and your daughter is the second owner. It's possible the first owner broke the skates in by riding the inside edges and now your daughter has inherited that stance along with the boots. The prior owners may have had the skates stretched, so the sizing is off. Look at the skates when they're not on her feet - the blades should be perpendicular to the bottom of the boot. The top of the boot should stand up pretty straight above the sole, not leaning or twisting.
You can try new laces, which will make tying the skates easier and more snug, but I don't know if it will fix the problem.
I tighten her boots as much as I can before she goes on the ice; her ankles seem a little small, as I don't seem to be able to tie the boot where it hugs her ankle.
Maybe the skate size isn't the issue, perhaps the skate is too wide for her, which is why the insoles helped a little. Superfeet insoles are thicker than Riedell's stock insoles, so they would "fill up" the void inside the skate and give her more control and a better stance when skating.
Get her feet measured, length and width, at the pro shop. Make sure they use the Riedell measuring tool. Blue Ribbon skates only come in Regular (B) and Wide (C), so you would have to order a different model if she needs a Narrow (A) width.
Is your daughter tall and/or skinny?
What level is she skating at now? (Jumps or spins she's learning?)