Yes, you could do that as long as you chill the brisket quickly in the refrigerator after the first smoking session. You could also finish the brisket in the oven the next day if you wanted. A big part of the smoke flavoring happens during the first half of brisket smoking anyway, so if you finished it in an oven, it would still taste good.
If you put it in the smoker the second day, take the brisket out of the fridge an hour or two before you put it in. It will warm up a little and finish off quicker.
