titchadesh

Today I was asked why do we say to someone wearing new clothes ! תתחדש - Titchadesh! The blessing is parallel to "Wear it in good health", but it literally means "renew (yourself)". How did this phrase come to be?

The Rama mentions in Orach Chaim 223:6 that there is a custom to say to someone wearing new clothes תבלה ותתחדש - tibale v'titchadesh. Other sources (quoted here and here) have תבלה ותחדש (this seems to me to be the more logical, perhaps the original.) The meaning of this phrase therefore means ''May you wear out (this garment) and buy a new (one).'' It is therefore a wish for long life.

Interestingly, the Rama writes that there are those that say that this blessing should not be said on shoes or clothes made of leather, because it is not proper to wish the death of another animal.
The verb בלה - to wear out - is the source of the term bilui בילוי - "recreation, pastime". How did we go from "waste" to "recreation"?

In Iyov 21:13 we find the phrase יבלו בַטּוֹב יְמֵיהֶם. Iyov is complaining about the wicked and how "they spend (waste) their days in happiness". The kri is יְכַלּוּ בַטּוֹב יְמֵיהֶם - "they will end their days in happiness". The verse has a negative connotation, but the phrase - through a misreading according to Amos Chacham in the Daat Mikra - has gained a positive sense, "recreation". I agree that there is certainly a linguistic change here, but I think perhaps more significantly over the years there has been a major shift in society's view of "free time". The entertainment industry could not have been contemplated not so long ago, before industrialization freed up so much of our time.