Adding more character to my characters

Here is a piece I completed last month for the portfolio:

It is part of a picture book project that includes a full dummy and a couple of other "finished" pieces. An art director has now seen it and deemed its character depictions lacking. After her excellent explanation, I am inclined to agree. One gets very little sense of a unique personality here. Neither the girl nor the cat really leap off the page. Soft and sweet as the scene may be, it is forgettable and a good example of why I need to ramp up my characters in general.

This evening I began sketching my way toward improvement:

The cat, Zip, is meant to be a highly curious and active guy. I heightened the color contrast of the cat's fur to reflect his bold personality and shaped the pattern on his back to help highlight his movement through the story. The girl, Penny, has a passion for drawing. I've opened up her face more to reveal its expressions. (If you click on the image, you'll see more detail.) I've darkened her hair so she doesn't fade into the cat's background. 

I need to live with the drawing a little while before I determine what else needs changing. I welcome any ideas/reactions in the comments below.

Next (tomorrow evening, if I have time) I will redraw the other two images I had "completed" for this picture book. Perhaps drawing  Penny and Zip in other scenes will give me fresh ideas for the image above.