For me I usually end up with a plateau when I've lost some weight and my body isn't burning as many calories as before (because I'm smaller!) but I'm still eating how I was eating when I was at the higher weight. In that situation it is no longer enough to create a calorie deficit for me.
What has worked best for me is to either eat fewer calories (if feasible), exercise longer (if possible), or increase the exercise intensity to burn more calories. Or, of course, a combination of all of them. I also track my food really carefully while on a plateau in case I've gotten a little sloppy on the intake part.