I wrote a note saying that I would run up there and check but didn't need to. Their website (http://www.ho-chunk.com/index.htm) says...

New Chips Coming!
Redeem your current ones today for cash!
Out with the old and in with the new! It’s time to redeem your current Ho-Chunk Casino blackjack chips because we’re introducing new ones this fall. As of October 31, 2003, we will no longer honor the current chips at gaming tables nor at other Ho-Chunk Nation Gaming properties. So redeem your chips today for cash! Just stop by our Cashiers on the casino floor before December 31, 2003, to redeem your current chips for money. After Dec. 31, we will no longer redeem the current chips. Look for our new chips coming November 1.