The easiest way to solve this problem is two-fold.
1.) Either pick an updating schedule that will allow you to comfortably finish a page without rushing, OR delay updating until you're happy with how the page looks.
2.) Be more disciplined when drawing. Every page of a comic is important, or it wouldn't be there. Even the pages that aren't dramatic are still important. Don't rush things just because you think they're boring. I think that drawing roof tiles is about as fun as watching paint dry, but I do have a bunch of buildings with roof tiles in my comic, so I have to draw them. I can't just flail my pen over the page and create a bunch of chicken-scratch and call it a day. Basically, don't slack off.
When you give your readers a bunch of nice-looking pages, they're going to expect that level of quality from you every time. If you start posting terrible-looking pages just because you can't be bothered to draw less dramatic stuff properly, they're going to be disappointed.
I usually say "don't re-do old stuff" because it's SO easy to get stuck constantly re-drawing - and I'd like to give that advice here too. What matters most is that you do better going forward. If your current pages look nice, those are what new readers will see first when they're introduced to the comic - and if they like those, they will go back and read your old pages - and when they do, they'll be able to push through pages that don't look as great, because they know it gets better later on.
