You need to strip everything and start over... I would recommend a good wash (use dawn or other dish soap to remove wax) and then clay bar, followed by a good polish with a DA and good pad if you can afford it. I use Meguiars 205 for light polishing or Meguiars 105 followed by 205 for heavy scratch removal / finishing polish. Then follow those with a good sealant (a good wax or even the nu finish will work fine).
After this point your paint will be clean and polished and with good washing technique you should be able to keep things looking good. Wax will need to be reapplied every month or two (other types of sealants can last longer Ive never used nu finish so im not sure how well this will work) and you can touch up before waxing with a good polish if you need to remove swirls or any other defects.