How much does it cost to replace the entire cooling system with radiator?

"Entire cooling system" isn't relevant. That would include engine tear down and resealing cylinder heads and securing coolant passages. Replacing engine core plugs. All that to say that replacing parts that aren't suspect is never the answer. Having a technician troubleshoot the vehicle and determine what the needs are is the only smart direction. Contact a local technician or shop near you for real world quotes on all cooling system hoses - heater hoses - radiator hoses. See if your radiator has a flow concern or leak -- if neither are an issue, it's fine and doesn't need to be replaced. A thermostat replacement isn't a bad idea if it hasn't been done in quite some time. Other than that, seek specific resolutions for specific problems.