If you're still enjoying making it I'd say figure out the complicated and confusing parts & make some charts/timelines/etc. you can reference. If your readers are getting confused you could try giving more explanation to elements that haven't shown up in a while in the scene where they reappear, or put a "previously on..." type thing at the beginning of chapters to remind readers of relevant info.
Art-wise, as long as you keep drawing you'll also keep improving. So if you're making a long-term project you have to be okay with the fact that the art in the beginning is going to look different (and/or worse) than what you're drawing currently. If it's really bothering you, maybe try doing some shorter projects before coming back to this one.
