Renaissance wax which should do the trick. I've treated several rust prone firearms with Flitz and Brasso to help prevent corrosion. Before going forward with any of those, you should make sure that the Parkerizing will not be damaged, I can't see any of them harming the Parkerizing as they work wonderfully on blued/stainless guns, but hey it's always best to be sure.
Regarding getting the gun re-finished, that's up to you. I'm a big fan of more "resiliant" finishes on guns as my sweat is severyl corrisive (everyones body chemistry is different ya' know) and I have to be very, very careful with my carry guns that don't have a more resiliant finish.
I'd take a look at Melonite, Ionbond DLC, Robar Roguard or NP3, Wilson Armor Tuff, hard chrome, etc. those cost more. If you want to give Durakote/Cerahide etc a try, more power to you, but again check, double check, and tripple check on how those add ons will adhere to the parkerizing before going forward with refinishing.
I would try using the checmical polishes /preventitives first, see if that helps, atleast in the meantime it should prevent corrosion while researching your options.