回複：HELP! I140 denied, ask advice!

Whether you should appeal really depends 99% on why your case was denied.
If the denial is USCIS mistake, do appeal and AAO will reverse the error and granted your I-140 approval, in this case your I-485 can be reopen so you don't need to refile and pay the fees again.

If the denial is really officer's judgemental call and your case is not very strong, appeal chance is not good. It will be better you file another I-140, but this time you can't file I-485 because of you won't have a current PD.