Nothing much can be done at your age...try this it might help you... Exercise at least five times per week. By using exercises that help with gaining height, you will naturally increase the level of growth hormones in your body. Certain weight training exercises, high intensity sprints and bar hanging can help you achieve this. you must strengthen your abdominal and back muscles first to get the most out of your exercises.
Eat a healthy diet.you have to eat more foods high in amino acids to help increase the levels of human growth hormones in your body. Adding calcium, zinc, iron, copper and magnesium to your diet can help you increase these levels as well.