You should periodically check the temperature settings on your oven. Put a reliable oven thermometer inside and heat the oven to say 350 degrees. If the thermometer registers more then seven degrees above or below this, it might be time for a new sensor ,thermostat or even an element.
Also did you know that replacing a burned out oven element is a very easy process? In most modern ovens they are held in with two 1/4 nut heads and two wires plugged or screwed on the the element. Compare the price of a new element to cost of a new oven, then give us a call.