If your nursing assistant certification has expired you most likely have to retake and pass the CNA exam. In some states you are required to retrain, especially if your status has been expired for more than two years. Federal regulation requires that an individual work at least eight hours, for pay, in the provision of nursing services without a two year break to remain active. Please note that renewal requirements may differ from state to state and may change over time and that some states make a distinction between inactive and expired CNA licenses. Locate the contact information for the CNA registry of your state and and ask them what you should do. They are the ultimate authority when it comes to CNA licenses since they issue them.