Well, dont want to blame anyone or to make some PANIC, but dont everybody notice that games lately is a little..."questionable" here? Blueberry Garden, Love+...these games not bad, but they sure is niche games. I noticed, that lately sales barely keeping around ~1000 of item each game, little more or less. I dont see sales progressing at all. I dont know real statistics but it feels like 90% of purchases made by same peoples again and again, some core IGS fan audience.
Definitively, i understand that IGS is not as big as HumbleBundle, so it would be a little hard to bring here "BIG" game like some of appeared on HIB, but it still feels like IGS really lacking promotion. Most of my indie-gaming friends not ever heard about IGS and even most if "indie bundlers" - too.
So, that i can suggest is
1) try to become a little more known. In example there is sites that tracking indie bundles, IGS should get recognised by them too
2) try to attract some a little "bigger" games. I dont have anything agains pure hardcore indie like Love+, not-game-at-all like TRAUMA or even experimental Blueberry Garden but indie is not only platformes and not always hardcore and not always 100% niche. Sounds probably like "please less indie!" but i hope you dont get it wrong.