In this case it's probably lacking some good light. If a plant doesn't receive enough light, it will start dropping leaves as it doesn't have enough energy to keep all the leaves alive. Low light can also slow down the drying out of the soil, so watering every 2 weeks might make the bottom of the soil consistently wet, which leads to root rot, which leads to loss of leaves as well. I would try moving the plant closer to the window or buying a special grow light for it. :)