I am running an external analysis case and I am cutting my geometry in half because it's symmetric. Is there a way to mirror back the results so that they have a better appearance.

Yes there is. First use VREFLECT and CGEN to build the missing half. If you have the latest prostar you could even try CVREFLECT to do it all in one step. Then you can use DGEN to generate data over the newly created cells. Be careful - dgen does not reflect velocity components - it simply creates the exact same data on a new cell/vertex location.