As you level, take the armor you get from the heroics or flashpoints and rip the mods out of those. Then you can take those new mods and replace them with the mods you currently have in your Revans set. The amount spent for ripping and replacing the mods is negligible compared to the purchasing the new set of mods.
Just a quick question though... I noticed you said you have Revans mask which usually runs for a couple mil in itself (unless you were lucky enough to find on in a pack, then disregard this last message). If you purchased the mask, then why are you worried about credits because you obviously know how to make credits.
THANK YOU SO MUCH. I did what you said and my revans armour (now lv 37 )has at least a 200 more armour than average Green, Blue and even purple drops