Back Fat?
unfortunately Nate is right.. you can't spot reduce fat.. the best way to get rid of those back boobs is the same method you used do drop weight everywhere... watch the intake and in general cardio/calorie burning. Lat and lower back routines will certainly add muscle and can also help with the caloric deficit you'll need, but they won't force the body to burn back fat, anymore than crunches will force the body to burn tummy fat.