"What should I do to get abs?" I am still asked this question more often than any other. Although the question is often phrased differently, the answer is always the same: Seeing your abs – or any other muscle group for that matter - is strictly the result of having low body fat levels. You get low body fat from proper diet and cardio, not from doing hundreds of ab exercises every day.
It may seem like your lower ab muscles are hard to develop, but it's not really an issue of muscle development at all – you simply store your fat in the lower abdominal region more readily than other parts of your body.
Most people don't have their fat distributed evenly throughout their bodies. Each of us inherits a genetically determined pattern of fat storage just as we inherit our eye or hair color. In other words, the fat seems to "stick" to certain areas more than others. Men often tend to store fat more readily in the lower abdominal region (the "pot belly"). In women, the "stubborn" areas are usually the hips, thighs ("saddlebags") and the triceps ("grandmother arms"). These are the first places the fat goes to, and the last places the fat comes off.
You could focus on more "lower ab" exercises like hanging leg raises, reverse crunches and hip lifts, but even these won't help as long as you still have body fat covering the muscles. You can't "spot reduce." I would suggest cutting back the volume on your ab training and spending the time on more cardio work instead. Personally, I do about 15-20 minutes of ab work two times per week. (About 8-12 sets of 10-25 reps). Here is a typical ab routine that I use:
Hanging leg raises 3 sets, 15-25 reps
Hanging knee ups (bent-knee leg raises) 3 sets, 15-25 reps
Incline Revere Crunches 3 sets, 15-25 reps
Weighted Cable Crunches 3 sets, 10-25 reps
For maximum fat loss, you should do cardio 5-7 days per week for 30-60 minutes. You could continue running or mix up the type of cardio you do (stationary cycling, stairclimbing, elliptical machines, and other continuous aerobic activities are all excellent fat burners). Once you are satisfied with your level of body fat and your abdominal definition, you can cut back to 3-4 days per week for 20-30 minutes for maintenance.
As far as diet goes, here are a few fat-burning nutrition guidelines in a nutshell:
Eat about 15-20% below your calorie maintenance level
Spread your calories into 5-6 small meals instead of 2-3 big ones.
Eat a source of complete, high quality protein with each meal.
Choose natural, complex carbs such as vegetables, oatmeal, yams, potatoes, brown rice and whole grains. Start with at least 50% of your calories from complex carbs and reduce carbs slightly (esp. late in the day) if you are not losing fat.
Avoid refined, simple carbs that contain white flour or white sugar
Keep total fats low and saturated fats low. Aim for only 15-20% of your total calories from fat. A little bit of "good fat" like flax oil is better than a no fat diet.
Drink plenty of water – a gallon is a good goal to shoot for if you are physically active.
1000+ reps of ab work four days a week is an amazing feat of endurance, but that's not how you get abs! You probably have outstanding development in your abdominal muscles. Unfortunately, if your abs are covered up with a layer of fat, you won't be able to see them no matter how many crunches or sit ups you do. You "get abs" from reducing your body fat and you reduce body fat mostly through diet and cardio.
Training routines and diet/nutrition are covered in detail in my book Burn the Fat, Feed the Muscle (BFFM)