I'm only saying this because I believe it to be true.
The new auction house might end up being a large flow of steady cash for you but just in case...
There are ways of shoring up the books without having to create some new cash grab every 3 to 6 months or so. The best way of course is to create a larger stream of constant cash flow.
Vips are that stream of cash flow and instead of having them dry up you should attempt to open the floodgates.
First come the always asked for perks. I have no suggestions other than they be nice and unbuyable by any other means.
Second come the free turbine points. Get rid of them. That is part of the reason the perks need to be nice. Make Vips purchase all of their points just like anyone else. You are giving points to subscribers they can buy their way out of their subscription with.
Make vip attractive enough that a player who has bought everything would still be tempted to subscribe. Make it attractive enough that when new incoming players decide to spend money vip looks like the best option.
Raise the price as well if you need to.
Hopefully between selling the items in the store, the asah, and an influx from vip subs we would be generating enough money for you that there will be no more need for cash grabs.
As an afterthought change the title of the payment plan from ViP to simply Subscriber please.