The first thing that we notice about the Lizzie who attends Grade School is that she's as much an outcast as Michael is but for a different reason. Instead of being a wise-ass who is too blasted stupid to realize that all his being eager to do any fool thing just makes the cool kids feel even more contempt for him than they already had, Lizzie's natural timidity, possessive nature and sheltered upbringing mean that she's pretty much on the outside looking in when it comes to the social order.
The problem is that she shares an unhappy tendency with Elly: the tendency to blame her outward appearance for the fact that her life isn't as happy as it should be. We know for a fact that Lizzie used to be able to trade on her looks to get what she wanted and when people stopped scurrying around like mice and no one was told to let her win because she's a cutie, Lizzie simply can't hack it. Rather than accept the fact that despite being appealing in a sort of wan, clunky way that she can't bat her eyelashes or whine her way to success, she thinks that if she were pretty again, life would go back to normal.
Not, of course, that she admits to herself that that's what she's doing. The Liz who looked as if she might break free of home set herself on the teal-and-lavendar trajectory of repeating the mistake Elly made when she blew her stack because someone Franco-Ontarian accused her of consciously doing so.