You wouldnt want to replace the valve springs unless you were going to build the motor for high performance or if it had high mileage. This is because the valve springs have nothing to do with the engine burning oil. What would cause that would be the valve seals. You still have to pull the springs, but you would not have to replace them. Other than that the only other things i could think of that would cause a motor to burn oil would be the rings like Justdriving said or a blown head gasket but you dont seem to have any symptoms of that.