What do you do when visa expires? Just apply for a new one? Is it possible to get longer than a year

After your current one expires, you should apply for a new one to enter China. If you want to travel in China for multiple times, you can apply for the mutiple-entry type for one year, two year, three years, five years, or even ten years. As the consulate does not offer return mailing service, you can entrust an agency or other individuals to collect the passport for you.