i lightly microwave glycerin soaps (colonel conk, for example) to melt and re-form them. it doesnt take long at all. to make sure they dont burn, i only microwave the soaps in 5 second intervals or so. when they melt, i gently stir while pouring into a ceramic bowl. then i just let it sit for a while until it re-forms. Ive been doing this to col. conk soaps for a while and found it doesnt affect the integrity of the soap or its fragrance.
i dont know how to re-mill/re-form a triple milled soap, or any non-glycerin soap for that matter. ive even heard from others that melting non-glycerin soaps in the microwave is a bad idea, so perhaps other guys could chime in on this.