yes - log food and figure out how many calories you're currently averaging a day - and cut back gradually from there until you start losing again. Once people are out a ways from surgery, the number of calories it takes to maintain or lose varies tremendously depending on a lot of different factors, so you'll just have to experiment to find your range. I can maintain on 1700 and lose on 1500, but that seems to be on the high side for women. A lot can only eat around 1200 to maintain. So again, you'll have to experiment to see what level works for you.
and yes - increasing exercise can help a bit (and is great for your overall health), but as they say, weight loss is 80% diet and 20% exercise, so you'll have to adjust your food intake as well.