I don't mean a dedicated video, I mean start each video with something like "How was everyone's weekend? Tell me in the comments if you did anything cool". Ask them to comment the answer to literally any question. Might improve interaction/activity.
Schedules are great if you have the time to keep to them. Personally I won't have a schedule as I don't want the pressure to HAVE to upload at particular times. I try to stick to one video a week minimum, but not on a schedule.