I once had an unexplained jump...when I replaced a fridge with a newer one. The new one was "auto defrost", which was one reason it required more power.
Any new appliance can use much more than the unit it replaces. In the 'old days,' when you turned something off, it was off. Today, many appliances (such as TV sets and fluo lamps) achieve their "instant on" by actually continually using some juice to keep the electronics 'on'....it may be only a few watts, but watts add up.
So, I would ask if there were any new appliances.
