I would leave it on so it's still providing bright light. You can cut the heat output by raising it higher up or possibly dimming it using a lamp dimmer or dimming thermostat.
As the seasons change, it is usually necessary to make some adjustments in the bulb wattages or the distance of them. It's important to make sure you are using either a temperature gun or digital probe thermometer to get accurate readings. If you're using a round gauge (dial), those are very inaccurate & can be off 20 degrees or more. So if that's the type you're using, the basking surface temp could actually be closer to 140 degrees. In that case, you would definitely need to use a lower bulb wattage during the hotter season.