I feel your pain Grammy! Lately it seems like I jump from one plateau to another. I have been trying to "mix it up" a little too. At least 2x a week I try a new video or exercise from SparkPeople. I'm down almost 40 pounds now and it's getting harder.
I remember when I would sweat buckets doing 3 sets of 20 crunches (and my elbows were no where near my knees)Now I can do 5 sets of 50 bicycle crunches and I have to do them very slow and steady and concentrate on them to break a sweat.
I go through phases of being bored/lonely/unmotivated so I come here and peruse the boards reading and grabbing all the motivation I can.
Last week I lost 100 grams which was nothing I couldn't achieve with a hefty fart LOL
But I lost 1/2 an inch in my waist and another 1/2 inch on my thighs, so the progress is still there, just not measurable on the scale like I (always) want it to be!!
Hang in there, you can do this. Shoot me a message anytime you want. I'm right there with ya!