One of the main problems is still that we need new player to keep the game alive. Offering the old boost health and energy boost units is a good way - but this is for already more addicted new player because not many will spend this amount of real money into a game they have just started.
At the moment there is a big gap between player with Gingerbreads and those without because those without (especially on lower level) can not afford the new units and equipment that others can buy for gold in the store. Those that missed the Gingerbreads have no chance...
So again I ask you to make the gingerbreads permanent available in the store - and please also a permanent possibility to get at least a 2nd upgrade. This would give new player the chance to test the game for free - than decide if they want a bit more by buying the cheap gingerbreads and the possiility to do 2 upgrades at the same time (this one should also be cheap - think there was a unit for 100 gems in the store some time ago....)