I don't. I eat the same 1500 cals/day regardless of exercise. I exercise 6 days a week, mixing cardio and 3 days of resistance training (some days I do both). It's a balance, because I want to be sure I'm eating enough to build muscle, but at the same time I still want to be losing fat. I don't lose 2 lb/week, but at this point I don't really expect to.
The only exception to my 1500 cals/day is that sometimes I do a class at the gym after my workouts, just because they're happening then, it's fun and I have nothing better to do

(This is usually some kind of dance-y thing, not something really intense). If I find that I'm SUPER hungry later, I might throw in 150-200 extra calories of something with a lot of protein to off-set the difference.
But that's just me

.