FTM Underworks Binder advice?

I recently ordered my first binder from underworks.org/ftm I've only worn it a few times and the binding effect is weakening. (It worked wonderfully the first time and made me completely flat, but now its obvious that I am binding.) Perhaps from stretching it out while putting it on and taking it off? I considered hand-washing and then putting it in the dryer on the lowest setting for a few minutes to tighten it back up but the website's care instructions say not to put it in the dryer. Any guys out there have any suggestions?