When I lost the first 20 pounds or so my weight loss slowed. I found that to keep it going, that I had to slowly increase the duration of my exercise, or the intensity-because you want to get "fitter" and not stay the same level of fitness. Did that make sense?
When you start exercising-it is a struggle. After a while your body becomes stronger and more fit, and you have to do more to progress further. If you started out doing 20 minutes on the treadmill...then a couple months later you should be doing 30 minutes on the treadmill, or 20 at a quicker pace or higher incline-something to make your body have to work harder again.
Same goes with weights-if you started doing a strength training video with light 2 or 3 pound hand weights-then 6 months later you should have progressed to something a little higher. If you are no longer feeling the muscle fatigue and failure by the end of a certain set of exercises-then your weights need to be increased. If your program includes floor exercises for the legs and buns and you aren't struggling as much as before-then get a set of adjustable ankle weights to add more resistance. Start out with them adjusted to the 1/2 or 1 pound mark...and when that gets easier, add more of the little weighted bags to them.
Alternate your cardio exercise-if you normally walk, then alternate rollerblading, jumping rope, trampoline, dancing, or some other cardio activity. They all work the muscles slightly differently and will challenge the body.
I also find that I lose better when I eat "cleaner"-staying away from chips, ice cream, and low fat "treats" even if I am staying in my calorie range.