No, if they approved your initial site then you can add away - even to new domains. If you are using a CMS then the ads should be reapplied automatically. They will spider your site to identify the change in topic and change the ads accordingly. You don't have to do anything. have fun and good luck
Once you r approved.. u can use the code on any website (as long as it doesnot go against the agreement) and on any page .. ???????????????