If you could what routes would you rework/add content to?
Various folks bringing up Cindy & Wade make strong points, and I'd be fine with more consistency in what we have so far, and a better sense of direction for their relationship (and in general a more-clearly-defined take on Wade's character). I also take the point that we don't really know what Eva is up to with them long-term, and if their relationship could be saved or whether it will be canon that it's doomed. (I personally think it's more interesting if their overarching story is how and why they break up, something you rarely get in a VN in my experience, but I also see why that is a minority opinion.)
In terms of who should be getting more content, I'm very tempted to say Emma, partly because she's got a great personality, partly because I think there are many paths which would be made more fun (sexually, dialogue, outfits, etc.) with her involved.
But at the end of the day, there's one clear choice. The major untapped - in multiple ways - character in the game as it stands has to be Ivy. Putting someone who looks like her in the game, giving her the job she has and the outfits she has, giving her the personality she has and the attitude about sex she has, but NOT having any primary storylines revolve around her and NOT having any on-screen hetero sex with her this far into the game is a major mistake. I get that Eva sees her as a crucial but secondary part of Lena's story, and I appreciate her guiding Holly to be more sexually forward and active. I think all of the sex Holly and Lena can have with her is awesome! But to not have any men involved in her sex life - and a blowjob for Jeremy just to piss off Louise doesn't count - is a real waste of opportunity.
Two possibilities missed, off the top of my head:
1 - Stalkfap Meet-Up. Back in chapter 5 or 6, Lena's getting into Stalkfap, has options to post nude photos and interact with patrons over private messages. "You could do more," Ivy says. "What do you mean?" Lena replies. "Well, be in the alley outside Blazer tonight at 1am when I'm off-shift. Hide in the doorway a few doors down." Lena goes and it turns out Ivy is meeting for a little one-on-one time with one of her biggest supporters, just some guy. Ivy winks towards the hidden Lena as he gives Ivy a wad of cash and then, Ivy places her hands against the wall, spreads her legs, and starts giving instructions on what exactly she wants him to do to her...
2 - You're Not Interrupting. A little later, chapter 8 or 9 maybe, Lena calls Ivy for something. There's heavy breathing and some moaning from Ivy's end. "Oh, you're not interrupting. Would you like a little peek?" And Ivy sends Lena real-time photos, selfies and maybe one or two in part of a mirror, showing Ivy giving a blowjob and then getting fucked. Ivy never shows the guy - "he's just some guy" - but in one photo there's a small bit of the guy's dark hair. No hairstyle, no skin tone, just the dark patch of hair in a corner of the photo. Can you imagine how much we (and Eva's patrons) would lose our shit trying to figure out who Ivy is screwing? Ian has brown hair so it's not him, but Wade, Perry, Stan, Mark, Robert...and Mike... all have dark hair. ("It's got to be Perry, remember how Ivy was weirdly really nice to him? She's totally 'training' him in secret, the same way she is with Holly!") And of course we get the payoff a few chapters later, which causes major drama if a player's Lena is also screwing Mike.
As with Cindy and Wade, we don't know Eva's endgame for Ivy. We've talked for a long time about Billy's "new modeling agency" being a potential prostitution ring, and that's still possible. There may yet be real fireworks to come between Ivy and Cindy - maybe including Wade and/or Axel - because of the Wildcats contract. There are hints of interest between Ivy and Ian, if you play your choices that way, but frankly that's been way too long in coming also. (There may be some mockery of SerHawkes around here for being obsessed over this possibility, but the man has a point, and it's a strong one.) You just don't put someone as forward and sex-positive and sex-hungry as Ivy in the game, with the whole "I'm just drawn that way" vibe to match, make her both a dancer and a Stalkfap star, and then give her so few avenues for actual sex, and none of them with men.