I've seen this title on your website and promotional screenshots. Youtube and Twitch also recognize it as "Reflex Arena", but everywhere else is just the old, plain and simple "Reflex" name.
Well, if that is your idea for the new name, I'd say just leave it as Reflex as it is more clean and it sounds cooler this way, just like the name "TheFacebook" became just "Facebook". Look at the other arena shooter names: Nexuiz, Xonotic, Diabotical, Painkiller, Quake, Doom, etc. Plain and simple names. Btw, Reflex Arena seems to make a reference to Quake 3's full name, which is Quake III: Arena, making it an unoriginal name, at least in my opinion(don't get triggered).
If it's not then, well, forget about what I said. I just want to clear this out since I've seen no forum topics about this.