Kay, as I see it, a problem at the moment is keeping people active or involved. So.. how about.. if you log on every day for at least 30 mins total (or something like that) for a month, you get a reward? This won't benefit stronger, older players more than it will newbies, but just reward activity. Something like.. 5 DDs or 20 ECs. For every consecutive month, it goes up. I'd suggest a CD reward but the worth of CDs fluctuates so much whereas there'll always be a need for DDs or ECs and it'll always be worth something.
Make referral points worth more, too, to get people referring if they can.. possibly give a bonus to referred players for reaching level x or y IQ. I'm not sure if there is a reward for referred players at the moment, can't remember as it's been so long.
Maybe every so many levels there could be a bonus of an ec or something, every 50 maybe.
Oh, and not entirely related, maybe you should limit how many CD lotto tickets one can buy? Max of 100 or something, to make it more fair.
Also, FIX CHALLENGES please. That's a good one for activity.