OK, I'm going to tell you what's worked for me, so take everything I say with a grain of salt.
The first thing I do is assemble the stats into a battle plan. The plan starts with my current weight and body fat percentage, and the body fat percentage I'd like to be. I don't know what your target is, but for the purpose of example, I'll use my target, which is 13%.
At 214 lbs, your body breaks down this way:
Fat body mass: 71 lbs.
Lean body mass: 143 lbs.
From this, we can get your target weight: 164 lbs. The formula for this, by the way, is:
lean body mass / (1 - target body fat percentage)
So that means a projected loss of 50 pounds.
The next step is establishing your rates of calorie expenditure. If you use an like this one, it comes to 2,019 calories. Now multiply that by 1.2, assuming you have a sedentary job, to get the amount of calories you burn in a day, without exercise: 2019 x 1.2 = 2,423 calories.
Now multiply that by 7, to get your weekly expenditure: 16,961 calories.
OK, now let's look at weekly exercise:
elliptical - 6 x 600 calories = 3,600 calories
yoga class - 2 x 250 calories = 500 calories
ab class - 2 x 250 = 500 calories
biking on sunday - 500 calories
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Total for week: 5,100 calories
Obviously, I'm making some guesses here, but you get the idea. . .
Total calorie expenditure, weekly: 16,961 + 5100 = 22,061, or 3,152 calories per day
In other words, if you eat the equivalent of 3,152 calories per day, you shouldn't gain weight, and you shouldn't lose it, either.
Now, how much can you cut from that safely, i.e. without cutting into your 142 pounds of lean body mass? I assume you don't want to do that, especially being a former athlete!
My rule of thumb is 10 calories per pound of fat mass. You have 71 pounds of fat, so that would mean a cut of 710 calories a day. From this, you can get what your diet should be, in terms of calories: maintenance - safe cut = daily calories :: 3,152 - 710 = 2,442 calories per day.
So the first thing that really jumps out is that 1,500 calories is about 900 calories too low for you. This alone may explain why you've hit that plateau. What's happening? Well, a couple of things. First, you're probably cutting into your lean body mass, which is making you weaker overall, which means your workouts get progressively less effective. Second, you're starving yourself, and your body will do all it can to preserve your fat. Remember, we survived as a species not from building muscle, but rather from preserving fat.
If you've been doing this for a long time, you may have to take a month or so just to reset your metabolism using the new figures. Naturally, you would have to tinker with them -- up or down -- but you get the idea.
Next, I would vary your cardio workouts. Do some interval training. Try different machines. Your body adapts to the same exercise day after day.
Do you take breaks from exercise? If not, do it! Your body needs a rest.
Take a look at your weight routine, and reexamine that "core ab class". Six packs are the result of 12% body fat, not millions of crunches. You can exercise your abs just like you would any other muscle, e.g. 3 sets of 10 swiss ball crunches twice a week -- that's really all you need.
If you're not doing complex muscle exercises like squats, deadlifts, presses, rows, pullups, etc., take another look at your weight training as well.
The older you get, the longer your plateaus can last. I'm 58, and my plateaus typically last more than 30 days. But with the right nutrition and exercise plan, you can and will break through them.