I've been asked in the past many times, 'How can you replay VNs?' and 'Isn't that boring?'. In fact, I get asked that a lot with my 'Random VNs' posts. I thought I'd answer this question...
Replaying VNs is a matter of passion. To be blunt, if it is in a genre I don't like or hits my pet peeves too hard, I can't bring myself to replay it. The fact is, VN experiences don't change through multiple playthroughs, and in this way they are much closer to a book than to the interactivity of many games.
Something I should make clear is that I am a story-lover above all other things. I don't just mean that I love games, anime, and VNs for their stories... I mean that I'll do practically anything to experience a good, well-presented story. Hell, I learned Japanese for that reason.
This is actually the reason why I have so much trouble with pure romance, mystery, and charage. These three types of stories follow some of the most 'confined' story patterns in existence, with a very limited selection of story elements, and as a result they are far easier to predict than many fantasy, sci-fi, or even conspiracy-drama stories... at least for me. This is particularly fatal for mysteries, since a lot of the attraction of the genre, at least to me (when I still liked them) was how much trouble figuring out 'whodunnit' or 'what is going on'.
Now, I have become experienced enough that very little surprises me. Particularly, in the last five years or so, this trend has become marked in my own subjective point of view when it comes to VNs. The issue now is the subject matter... what do I enjoy enough to experience pleasure with on a second run? The genres I can take pleasure in on a second playthrough are limited... almost entirely to the sci-fi, fantasy, and conspiracy genres. Rare exceptions exist, but that is due to a sheer, overwhelming level of quality or due to a powerful emotional experience that doesn't fade quickly through multiple playthroughs (Uruwashi no is an example of this type).
To be blunt, with most VNs, replaying them is impossible. There are no new angles to explore, the feels no longer touch me, and I honestly have no interest in re-experiencing slice of life scenes, lol.
So, it comes down, as I said above, to taste. I can replay VNs i love multiple times. However, I will never be able to replay say... Subahibi or Aiyoku no Eustia.