It's really a combination of a few factors.
Like Zeppelin says, the use/abuse of the reverb really dates things. But I think the way your voice interacts with the reverb kinda' does the same thing. I mean, I instantly thought "Simple Minds" the second I heard Neon Lies, and it has a lot to do with your voice. And even without the reverb, I'm thinking David Bowie. Lots of Bowie going on with your vocal style -- and it's not so much the Ziggie Stardust or modern Bowie, but more the 80's "China Girl," "Modern Love" kinda' Bowie.
You might work on not "swooping" or scooping so much into your phrases . . . ya know what I mean? Your voice kinda' starts out with this low-pitched growl and then scoops in to the note at the beginnings of all your phrases. That, again, subconsciously makes people think of Bowie or Simple Minds, which makes them think of John Hughes films (and
the Brat Pack) which makes them think '80s.
Finally, the keyboards have gotta' be updated. That's an obvious one. Also, try different drum samples -- preferably something a little more natural / believable sounding. And don't record your guitar direct, either. Stick a mic in front of a real amp. Does wonders.
Honestly, what I would do is work it. If people think you sound 80's, then make that your trademark. Start listening to more 80's records, and try to pick up on even more things. Make it your thing, dude. There's a lot of bands out there that are purposely trying to sound 80's and failing at it. You're already one up on them.