Tomcat 6 and foreign characters (UTF-8 and non UTF-8 mixup)

I have a problem displaying foreign language characters in web app with Tomcat 6. Previously we were using Tomcat 5.5 and we did not face this issue. To fix this issue I followed http://wiki.apache.org/tomcat/FAQ/CharacterEncoding#Q8开发者_如何学Go and made changes to my web app accordingly. Now the web app supports URF-8 encoding and most of the issues with encoding are fixed. The bigger problem that I am facing now is with the old data that is stored in the database using the app with Tomcat 5.5. The old data is not displayed correctly on the webapp with UTF-8 encoding. What is the best way to to have the webapp configured with UTF-8 encoding and also to be able to display the old data which are not UTF-8 encoded?

Also, the I am not able to determine what encoding was used previously. Thanks.