Unless more water or coolant are added, the freeze protection temperature is permanent. I would go ahead and change it out. The easiest way to do it is...
1) With a cold engine, remove the radiator cap.
2) Open the drain plug for the radiator and drain the radiator dry.
3) You can optionally clean your coolant overflow tank if you like by removing it and using dish soap and hot water. It takes patience.
4) With the radiator drain plug closed and the overflow tank back in, open any bleeder valves your cooling system may have.
5) Fill the radiator with either a store bought pre-mixed Dex-Cool like Prestone 50/50 Dex-Cool or make your own with straight Dex-Cool and DISTILLED water.
6) Once the radiator is full, start the engine with the heater on HOT and HI. Get back to the engine and close the bleeder valves once coolant comes out of them in a steady stream.
7) Top off the radiator and overflow tank over the next few days and get in the habit of checking both once a week.
You might repeat this process 2 or 3 more times so that the coolant is essentially "fresh".
