Naruto online, looses some of the fun, by essentially abandong the traditional gameplay concept, known as Grinding... We do love the sweep mechanic... but... if you want to do something, to get people to actually replay instances again, and restore some of the Good Ole "Grind for XP" feel that RPGs always had...
A... increase the drop rate for items in the in the Ninja exam, after you beat a level, if you actually go back and replay the battle, for jonin medal users, stop instantly clearing the the sweep, and give the the option to "Finish sweep" or "Stop Sweep" on the sweep window... this would give them the ability to stop and grind, or finish all at once, if they watned to as well
B... for plot/elite instances, if you have already beaten it, make it only require 5 stamina, if you play through the instance manually, rather then the usual 10 for sweeping
C... allow elite instances to still be played (But not swept) for XP and Coins, after completing the daily reward limit