Ok its a old game but it will be nice if someone can help me out

Ok so my chao reincarinated 1 time and I already gave it all 21 animals so my question is how do I reincarinate it a 2nd time? does it still have a chance of becoming a chaos chao?

I had the game since 04 and I still can`t get a chaos chao....

So if you can help me please comment thank you ^_^