Since you have a specific reason why this won't put you into a spiral of re-doing old pages (the old ones are in the wrong format, and once it gets to chapter 1 the format is correct), I would say, taking whatever time you can spare to slowly edit the beginning into the new format makes sense!! It's not gonna net you a bunch of new subs or anything, and some folks will re-read and some won't, but it'll make your work more cohesive to new readers. If you're able to do it, it seems like a good move!
If you're actually wanting to change a huge amount of the story and re-pace things..... I'm not sure what's the best way to go. If you do it edit-style, people aren't guaranteed to re-read, and even if they do it's a bit awkward to be reading a story and then have the storyteller say "wait, no, nevermind, THAT didn't happen, THIS happened instead!" in the middle of it.
Though I can say from experience that when I've been following a series for a while, and gotten really invested in it, and then the series suddenly restarts from the beginning to make it "better," that as a reader that sort of puts me off, and I've found I usually lose interest in comics when this happens. Like, I dunno, maybe it is better, but it's not the story I was invested in the first time around. I wouldn't do this unless you REALLY can't work with the story you had already.
At the same time, I've also been really into a comic and later discovered that there was an old version once, and the whole thing got reset at some point into the comic I now love -- I just never saw the old version since I found it after the reset and got attached to the shiny new version. So it can go both ways.
To some extent, a lot of this is gonna be a Follow Your Heart scenario. You alone know whether your early mistakes are hurting your passion for this story, or if going back and reworking things is realistically unfeasible for the amount of work you're able to do; whether rebooting the whole darn thing and not worrying about subs will be freeing, or if that would be giving into It Must Be Perfect anxiety.
Once you finish two years of doing your comic, you're going to look back and see new art mistakes, new storytelling mistakes, new plot things that you could've handled better, new pacing issues. After three years of doing your comic, you're going to look back at things that were new and good last year, and find all kinds of new mistakes again. This isn't something that's only happening because you're a new creator; it's never going to stop happening.
So make your decisions with that in mind!!
Personally, I think any time you can work with the decisions you've made already, and focus on moving forward, I consider that the best way to go. If there's a concept I didn't introduce well in the beginning of the story, and I'm on chapter 3, I'd rather look for a way to elaborate on that concept in chapter 3 than go back and retell the beginning. But my priority is telling this story in a way its audience can understand, rather than like, having a perfectly well-edited book when I'm done. Not everyone has the same priorities I do, and someone else might find a very different decision is best for them!