I would keep up the twice daily exercise. It keeps the metabloism up and you will continue to burn calories at a higher rate.
Also try interval training. Exercise at a high rate, for example 3 minutes, then for 9 minutes at a moderate rate. Then back to the high rate. Continue for your workout. I do this for about 20 minutes. Generally a 1 to 3 ratio is what is needed. So you workout for one minute at a high rate, its 3 minutes at a moderate rate. Your heart rate should be elevated during the high rate.