14 mo in, lost 72 lbs, need new ideas for weight loss

So, like my subject states, I have had a great deal of success with a slow, patient regime of diet and exercise to lose weight. I started with swimming, then realized diet would have to become a lifestyle change, played around with that for a while. Weight finally started to come off when I started doing exercise with impact. Once I had lost 35 lbs (which put me under 200 for the first time in 20 years), I started running and training for a half marathon (I had been a competitive distance runner for all of junior high and high school). I achieved that - weight loss, of course, got slower - running isn't exactly a huge pound-losing endeavor. I added strength training to my regime, where I have worked up to using 10 lb weights in each hand for most of an hour class - squats, lunges, all sorts of bicep/tricep/chest/back/shoulder work. I have gone from 235 to 162 - not complaining by any means. But.......I still have 20 lbs to lose - and I am realistic that it could take another year, or it may not happen at all. I have stalled, and my diet is staying consistent....if anything, I'm exercising too much - I take 4 strength training classes a week, 2 half-hour abs classes, plus I run at least 3 times a week for 4+ miles a piece. I do usually have a rest day each week.

I need ideas on what to incorporate to kickstart some more weight loss. I try to stay around 1350 calories per day. I try to keep my carbs under 100 grams, and my protein around 100 grams. My sodium stays under 2000mg each day. My fats might be a little high - since I don't love meat or eggs, and so a lot of my protein is cheese/dairy.

I have heard the phrase "lift heavy", but don't really know quantitatively what that means. Could that help my metabolism - to lose either inches or pounds or both? This summer has been a little frustrating - only 5 lbs lost all summer, so far. I could use some ideas.