As far as exercise goes, you may want to try adding high intensity interval training (HIIT) or Tabata intervals into your cardio workouts. A plateau in weight loss is generally due to the body becoming accustomed to its current routine. The high intensity mixed with the rest periods can help to jump start increased caloric burn during the day do to EPOC (excess post-exercise oxygen consumption). Here are two links to learn how to implement this type of training into your workouts:
From a nutritional perspective, be sure that you are fueling your body with complex carbohydrates, healthy fats, and lean proteins. This will keep your energy high during the day so you are able to work harder during the interval sessions. Keep in mind that pre and post workout meals are very important and can have an impact on how your body uses its fuel. Make sure to get complex carbs and healthy protein in a ratio of 3-4:1 within 30-45 minutes after your workouts. This will help you recover more efficiently and allow you to work out harder during your next session. Here is a great article about recovery nutrition:
Lastly, be sure you understand what a healthy body fat percentage for you should be. It is important to be a good role model of a healthy lifestyle in the fitness industry but it is also important to understand where to draw the line for your own health. ACE has some great tools to help you track the calories burned in your workouts as well as what your total daily caloric intake should be. Also, take a look at the body fat calculator to see where you’re at.