Sometimes we get into a rut and the way to break the plateau is to get out of the rut. Shake up your menus with new foods, new recipes, a new meal structure. Shake up your activity with new exercises or a new time for exercise. Your body might be "used" to the same old things and needs a change.
It might also help you to check to be sure you are doing what you think you are doing. Weigh and measure your food, use a pedometer, time your activity. I know that my brain likes to err on the side of fun and pleasure and my eyeballed half cup might be twice as much as what I thought I had.