Do what something called kickback, you lay on the floor feet about 3-4 inches off the ground and kick your feet up and down. Also, planks, and push up, and complete sit ups slowly up and slowlydown count to like 3 each time (up and down). Also, squats and lunges. And kettle bell (ball??) workouts can help.
Abs are made in the kitchen. You can do as many crunches as you can do all day , every day but that won't really cut it. You need to watch what you eat and try to eat as cleanly as possible. You will also need to pair up cardio with any kind of strength and ab training you do.