Even if you plan to restart, you're pretty much just doing the same thing AGAIN for the 2ND TIME in your new island, nothing new will be added in the game (other then brand new Mii's). In my opinion, I don't really see the point to delete and restart at all though... UNLESS you hate all the Mii's + childrens in your island and don't mind to re-put ALOT of time and effort again, then go ahead.