There are many reasons a super might want a new costume. The old one photographed poorly, inspired snickers in the passersby, or was trashed in a battle. Perhaps a new identity, or an alternate identity?
That happened to Mira. It all started in a Champions game, when Mira had become infected with nanobots. An obnoxious reporter named Power of the Press came by to see if he could get a story out of it. He had the finest X-ray vision in all Twinopolis, and nobody could keep a secret from him. Got lots of scoops that way. Nothing could stop his vision except Tupperware(tm).
So he checked out Mira, and saw all the micro-electronics, both the nanobots and her own computer-enhancements. And wrote a story with the headline "Bionic Bimbo Bugs Bugs".
This frosted Mira exceedingly, as well one might expect; so she decided the Bionic Bimbo was due to become Power of the Press' worst nemesis. By the way, the outfit Mousse is making for her is of Tupperware-derived fibers.