I would also like a new phone without paying anything. Unfortunately, it isn't going to happen for either of us. You are free to replace your phone, but you'll have to pay for a new one, either up front or on the tab.
If you balance is at 0$ you are able to use it again to get a new phone. You can put up to 360$ towards the tab, and you will get a monthly tab fee every month on top of your plan to be able to pay off your tab after 24 months.