100+ volumes from only six light novel series? I admire the dedication, but only reading extremely extended novel series is gonna wear you out real quick. You haven't really provided any genres you really prefer or titles to the series you've read, so I'll just give some general suggestions.
First and foremost, try some shorter series. Smaller series will look a lot less daunting to read than something with over a dozen volumes because you can pretty much estimate the time to get through it as only a fraction of a very big series. it's also a very nice break in-between big series. I do this quite often. After binge reading a whole library's worth of words in a long novel series, I tend to look for some short and light hearted novels to sort of refresh my reading palate so to speak. Stuff like cheesy romances or simple action stories are fair game.
Next, think about what you like. Do you like action? Comedy? Tragedy or dark stories? Cherry pick a few tags you feel like reading and type them down into sites like Novelupdates' search engines and browse their catalogue. Look through the tags that are there and filter away anything you don't want. Tragedy? Nope. Horror? Nah. Yaoi? Pass. After looking through all the novels you feel like, maybe you've got a small collection of novels to work with. This time, personally curate each one to see which ones are worth your time. Read through its description, look at some spoiler-free reviews, and maybe even read a few of the first chapters to get a taste. Don't rush, you're looking for a good book to keep you company for a long while.
Third, check out novels from other countries! Light novels aren't the only good reads around here. Korean novels (KN's) and Chinese novels (CN's) are also hosted fairly frequently here, alongside a few contemporary novels stylized in the same fashion as LN's, KN's, and CN's. You also don't have to look at only serialized light novels. Try browsing Royal Road or Scribblehub for stories that may pique your interest. Each different origin of novel gives a different flavor with the story, that is far too subtle and nuanced to be described in only a few paragraphs. Go check some out!
Fourth, lurk around some novel forums like this one. When you're logged in for quite a while on this forum, there are two links on the top left that are Show unread posts since last visit. and Show new replies to your posts. Every day, click on these links and see if any new posts seem interesting to you, or if another novel got an update. Click on any titles that get your attention, and see if that fits your fancy. After thoroughly reading through a majority of the novel gallery available, you might want to try this one out if you can't find a good read on your own. I usually take this approach myself.
Lastly, try reading stuff you thought you didn't like, or weren't interested in at first. Maybe you originally liked only hot-blooded action novels, and strayed away from romance or harem stories. Try testing the waters a bit with some of those and see if you can spark an interest. I've done this with shoujo novels and manga. As a guy, I'd originally failed to see the appeal in girl-oriented novels that talk of a girl's perspective through these stories, alongside honeyed descriptions of hot dudes. However, after trying them out, and reading a few damn good stories, I've begun to see the appeal these kinds of stories bring, despite it not being tailored to the demographic I'm a part of.
TL;DR : Read shorter novels, Tag search on NU, Read KN, CN, and western novels, Lurk in some forums, and read stuff that didn't catch your attention at first.
These are suggestions I give, based on my incredibly long history of being a digital novel reader. As awfully unspecific as I have been, I hope it helps you get dragged deep into this pit of hell muahahahaha.
