gewurztraminer tastes flat

I made a batch of el cheapo gwertz from the sun country juice concentrates. I followed the directions on the can, and I couldn't get the gravity high enough. (I even added a pound extra sugar but couldn't get gravity over 1.070) Anyways, it just tastes flat. It's hard to explain but it is missing something.

Is there a way I can save this? Is it too late to add white wine concentrate to give it a more grapey flavor, or is there something else I can do?

Well, the first thing I'd do is try some acid blend. To me, wines lacking in acid taste "flabby". If you want to see if acid blend would help, you could always pull a sample and add a little squeeze of lemon to it, to see if it helps it. Acid blend is a blend of tartaric, citric, and malic acid, so lemon juice isn't an exact sub, but it could give you an idea if acid is what may be lacking.

I'll give it a shot. I added acid blend when I first brewed it, but it could easily still be lacking. Thanks