It's obligatory to support the retina display of the new ipad?

I just finished developing a long project, universal (iPhone, iPod, iPad), and i didn't develop with the retina display on mind.

1. I'm forced to add assets to support this new resolution ?. If i'm using the latest SDK, can i specify whether to support or not the new resolution in the new ipad ? ( like modifying a value in the target device family for example).
2. If not, my app will show as the ipad version in the new ipad ?

Thanks !

You don't have to support the retina display, simply omitting the @2x graphic files is enough to have the iPad use the non-retina graphics. No further settings required.
Keep in mind though that your customers will most likely want retina display support, so you should consider adding the retina graphics at some point (if you want to avoid bad reviews).