I think that PTP is right-- she's getting what she needs out of the project and then it loses its importance to her.
An emphasis on "meeting your commitments" is only appropriate beginning in adolescence.
A lot of people who bite off more than they can chew and then have a million things half-finished (or just started) are serving an innovative impulse, too.
I'm one of those people. I am often driven to figure out HOW to do ________ (project). But once I've done that, there's little point (for me personally) in following through unless the product is something that I truly have a need for.
It's the impulse to problem-solve or create that I derive my gratification from. The process, not the product.
As for the library book problem, it may help for her to have a single location where she keeps books... or maybe a set number that she thinks she can read at one time. Have you asked if it bothers her when she doesn't finish the books?
