My VPIP is currently at 21.2 which I think is fine but my pfr is at 17 which isn't high enough. How do I improve my PFR?

The only thing I can think to do is to increase my three betting to the point where I'm three betting almost every single pot but that seems like a bad strategy. What is the proper way to increase PFR?

Current ranges are roughly:
RFI:
HJ-16%, LJ-21%, CO-21%, BTN-46%, SB-46%

Facing RFI: (Three bet/calling)
HJ/LJ - 2.5%/10%, CO/LJ - 2.5%/10%, CO/HJ - 2.5%/10%
BTN/LJ - 2.5%/10%, BTN/HJ - 2.5%/16%, BTN/CO - 5%/16%
SB/LJ - 2.5%/10%, SB/HJ - 2.5%/10%, SB/CO - 13%, SB/BTN - 18%
(No calling in small blind vs CO or BTN)
BB/LJ - 5%/27%, BB/HJ - 7%/27%, BB/CO - 7%/33%, BB/BTN - 7%/46%, BB/SB - 7%/69%

21/17 is fine, and at some stake levels (like 10NL) would be close to "optimal" in an exploitative sense. (A little on the tight side, but you'll crush the looser players).
Your RFI numbers look good.

FWIW, a lot of regs at 25NL or 50NL+ don't do much calling in position, and almost none in the SB. It's become quite common to have a "3-bet or fold" strat for every position except the BB, where you can call quite a lot. One of the reasons why calling with a wide range isn't very good is that people have learned to squeeze. In aggro games, you can't do much calling pre-flop, but there will still be a decent gap between your VPIP and PFR percentages, because you should be defending the BB vs CO/BTN/SB pretty damn often, so your BB VPIP will actually be quite high, while your PFR in that position is low.

Thanks for the response. Yeah I get what you're saying, the ranges were made for low to mid stakes games but I'm only playing the microstakes right now (2NL) so I wanted to know if I should be changing my preflop play to suit that better (e.g. playing more TAG and three betting more or not calling so much). What do you think?

I think I played 22/17 (or maybe tighter) when I did some 2NLzoom last year (12bb/100 or something, once I'd remembered how to play). I think you've probably got a great pre-flop strategy for crushing that limit, and by not developing the bad habit of calling too much you'll be in good stead for moving up too.

The regular tables might be a lot splashier than zoom. If you're still finding loads of villains with VPIP over 30, then you can open, call, and 3-bet wider, but it will increase the variance (both up and down) in your results. I think it's safer to develop a solid strat that won't put you into too many post-flop trouble spots. Naturally you can deviate against specific villains that you know how to exploit (e.g. 3-bet bluff more vs nitregs that fold to 3-bets too often, 3-bet thinner for value against stations), but 2NL is good place to become comfortable with a fairly "standard" pre-flop game. You can try out new things when you're crushing it.

Thanks man, that helps a ton. I've been struggling a lot with post flop recently so I appreciate the help.