Try buying the flavor concentrate and adding additional yourself if you have a flavor you like enough. It's also a great way to mask a flavor that sounded really good and maybe at first it was, but you've grown tired of it or it just doesn't seem to have enough punch to it. Chis has a good deal on small bottles of them.
10ML Flavor Extract - Lucky 7 Vapes
Do a little reading up on flavor percentages in the DIY section, or just post an enquiry there. Somebody will surely give you suggestions or at the least directions on where to find it.
Good luck
Interesting.. I've never heard of doing that (but I also don't really follow DIY stuff very much, just don't have the time) but I'll look into that. thanks for the info!