I haven't tried, but from what I can tell, you can't get ICA approval to return until you are out of the country. At that point, you join the queue of 20,000-200,000 people (reports vary!) who are trying to return to Abu Dhabi. My personal opinion is that unless you really really really have to leave, it's not worth the stress. Particularly as many (myself included) have been told that if they get stuck out of the country then they will have to take time off as leave.