Who do you want to like her?
Little girls and their moms? Hell if I know. I suggest trying to find away to actually market the books towards them successfully, then try figure out what they want.
Traditional comick book fans? Bringing back some kind of "sexy" costume would probably get the most immediate results. If you want to keep Carol in a conservative full body costume because you want sell Halloween costumes that moms will approve of, you could try having another heroine adopt Carol's classic outfit and Warbird name as a peace gesture. Moonstone, Ultra girl, and Star are the existing candidates; for what it's worth, I'd prefer Moonstone, and to see her return to being antiheroine while doing so. Kurt Busiek has said he would like to create a new character to take over her old look. I'd suggest you take him up on it.
Meanwhile draw carol with a distinctly feminine build while trying to tell good stories.