I don't actually mind having the same events over and over again, but maybe you should considering changing the prizes and ninjas for the events?

Like for the Lucky *.
The Naruto [Nine-Tails Chakra]’s Fragment have been on the Lucky * for the last couple of months if I can remember it correctly. If there were another ninja frags such as Ay (4th raikage) instead, I would probably max it out and spend 25k to get him. The Naruto [Nine-Tails] is sort of outdated, not popular as it used to be.