someone said (sorry forget who) that they wanted Gary and Greg 'blinkies'

Bringing back VIP could help. I'd sign up for it again. I know other people who would, too.

Once new items start coming, I think they'll see a significant bump in YC purchases. Also, a lot of people had a good amount of YC left over from the Zynga days, as there were no releases for a really, really long time.

Maybe a gift with purchase? People love free stuff and exclusive items. Perhaps making different items available for free with different spending levels could entice people to buy more than they otherwise would.

I'll think more and see if I can come up with anything else.