The last few pounds are always the hardest to lose, especially for athletes, because your weight loss and performance goals start to collide. As you have probably heard, you have to establish a caloric deficit in order to lose weight, but in order to gain fitness, you have to eat enough calories to support your training.
When I'm working with an athlete who has plateaued in their weight loss goals, I prefer to have that athlete focus more on training than cutting calories for three to four weeks. The idea here is that the physical adaptations you experience when you gain fitness actually allow you to burn more calories per minute during exercise, and in some cases, throughout the day (if you're gaining lean muscle mass). As your aerobic fitness improves, the size and number of mitochondria in you muscle cells increase. These power plants are where fat and carbohydrate are burned, and part of the reason you can ride or run faster and longer than you could before is that these furnaces can take in and oxidize more fuel per minute than they used to.
When you spend some time focused on gaining fitness, you have to make sure you're getting enough calories to support your training. You may not lose any weight for a few weeks while you're doing this, but think of it as building the infrastructure you need in order to take off those last few pounds. After you've gained the fitness (could be as short as three to four weeks or as long as six to eight weeks), then you can cut back on the calories and let that fitness work for you.
Why is this more important for the last few pounds of weight loss? Well, when you have 12 to 15 pounds to lose, or more, there's more "room" between the maximum calories you can eat to achieve weight loss and the minimum you have to eat to support your training. As these minimum and maximum calorie levels get closer, it gets more difficult to lose weight and still perform well in training. If you focus primarily on caloric restriction at that point, you might lose the weight (but as you have all seen, there are additional challenges with that method), but your performance will also diminish. Focusing on fitness at this crucial juncture will get you to your weight loss goal while retaining or improving your ability to perform at your best.