My younger daughter loved the Lab at age 7 but at ages 8 and 9 lost interest, unfortunately. (This may or may not be due to her sister going to Edge for those cruises; neither kid ever went to the Club.) We encouraged her to look for activities in the Navigator, and if your daughter is the planning type it may help to look at Navigators from similar recent cruises to check out what might be offered. On our last cruise, when she was 9, we scheduled a Palo brunch and told her she'd need to go to the Lab for at least part of the time (she has checkout privileges). If you have certain times when you have adult events scheduled, I agree with darnheather that it's fine to set expectations about your children being in the club at those times.
For our first cruise my younger daughter connected with a girl her age via the cruise meetup thread; we facilitated email communication between them for a couple of months before the cruise and they were excited to go to the Lab together. The social media stuff was really helpful for my older daughter too, and I think she still participates in a group message board with some Edge friends from last year's cruise.