The cost i'm not sure. But one thing for sure they would have to take apart the whole suit and then cut new lining for it. And the lining may be lighter material or half lining. And the sleeve linings would be changed too. Also if there are heavy padding inside, maybe changed to lighter one or removed altogether. Thinking of the job involved, i think make a new one would be better. Even if you want to retain the original one because of sentimental value. hehehe.

Declimatize is just a term i made up which came from some hardware related stuff. I do not thnk there is a term for re-engineering suits.