Java Class files in tomcat not linking/updating when using eclipse

I am working on an old jsp project. I have to modify it so that I can use it to meet my needs. I was facing issue while using any newer version of tomcat or java sdk. Therefore, I am using Tomcat 5.5.7 and java SDK 1.5. I have updated java class files of this project using eclipse helios (2012). But the implementation don’t show up in my project. Like when I change the database name and run the project it still wants to use the old database name. I have tried to upgrade the whole project to a new version of tomcat and java sdk but it doesn’t work. Can anyone help me with this?