Just so you guys can see where I was going with this, here's what I was thinking:
For the adult head, I thought the most muscular, largest rabbit head would look neat. Since that would best portray an adult leporid. But maybe even exaggerated so the Leverene is more than just a leporid. So I thought maybe a Flemish giant's head. With the asserting eyes and forehead of a buck, but the more prominent nose of a doe.
http://i7.photobucket.com/albums/y261/Balet66/Picture2-1.png
http://i7.photobucket.com/albums/y261/Balet66/Picture1-3.png
The brows stick up pretty far, though. I guess that's not too rabbit-like. I just thought it looked cool.
On the Leverene, the mouth was meant to become longer with each stage, and that's definitely not rabbit-like. It could be eliminated in the revamp. Again, I just thought it looked cool.
On the teen, I was thinking something along the line's of a lilac's head. And for the baby, something super cute.
The original Leverene didn't have a dewlap (the thing under the neck). It's something female rabbits have, but male rabbits can have a very small one, too (usually in the breeds that have loose skin, like Flemish giants and English lops). Once again, I just thought it might look neat on the adult and maybe the teen, and add some extra detail to fill out the artwork. =D
As for the fluff around the neck, my original idea was that it was almost nonexistent around the back of the head, and plumed at the front, but separated down the center of the chest. I thought it would make the Leverene look more regal if the fluff stuck outward over the cheeks in some poses. The back of the head was going to be completely black, and there was going to be an orange triangle that extended between the shoulder blades. Like on a tan rabbit (the markings are based off the tan pattern). So like this: http://i7.photobucket.com/albums/y261/Balet66/levstretch.gif
Although on some of my redraws, I was thinking of making the fur on the back of the head kind of pokey, an exaggeration of how the fur on the back of a rabbit's head doesn't lay flat. And I made the back of the head orange.
The body is based off that of a Belgian hare, or a real hare. Except it's exceptionally more muscular than a Belgian hare, with thicker legs and wider paws.
http://i7.photobucket.com/albums/y261/Balet66/Picture3-5.png
I thought the hare body would make it look more like a wild animal, and more interesting in general. But since there's some comments about it not being appropriate, I'm not sure what to do with it.
Overall, thanks for the ideas. I'm taking them into consideration. For the one that's being addressed about it not looking enough like a rabbit, I'm still not sure what to change. I have to agree. It looks more like an exaggerated hare. I rather like that look, though. =D But am working on it and won't settle until many more people are pleased with the result.
Also, I'll fix the shading. It IS too dark.