They eventually disappear.
I might have referred a good couple of hundreds (465), but now only 130 are listed as active, and only a third of that are what you can consider active.

Bump referrals? What's that?

Actually, they aren't deleted. I can see all of them in my referral page. They're just listed as not-active.

Inactivity - If your account should go to inactive status (90 days with no logins), ClixSense will consider the account abandoned and closes it. All funds in the account will be forfeited and the balance zeroed. Any referrals or ad credits that are in your account when it's closed for inactivity will remain in the account. While this account is inactive, any referrals in your downline may request to change their sponsor. If you reactivate your account these referrals who left your downline will not be assigned back, they are lost.

Looks like they added referral comissions to sticky ads (and made them more expensive)

As many of you already noticed we've recently made a couple of additions to our fixed advertisements' platform from our advertisers' most popular requests:

3 days fixed exposure
A few advertisers have asked for this exposure after we've automated the fixed advertisements' purchase process. Since we only had a one day exposure they would have to purchase three exposures to actually advertise for three days (which is a common interval between 1 and 7 days).
Not only we added the three days exposure pack but we also threw in a 3% discount that wasn't previously available.

12 hours fixed exposure
Many advertisers contacted us because they couldn't afford a $100 exposure and had to use other sites where they paid around 30% to 40% less. They told us they knew that even though the price was lower they were actually having much less views per dollar than they would have here but it was all they could afford, unfortunately.
Since we've always cared for our advertisers we decided to create a half-day (12 hours) fixed exposure that will fill this gap while providing the same premium service our advertisers love. This way they'll pay much less and can expect around 120k views (depending on several factors) in half a day which is much more than the exposures they would have elsewhere in a full day and even at a lower price.