For any personal tips you are going to have to give more info, because there are countless reasons to restart. From thinking the story would better shine in another medium, or art style..
Most common reason I see people restart a series is because they did not properly outline their plot or understand their characters. They write themselves into plot holes or into a way different story than what was imagined altogether. I stress this because I commonly see people say plotted when they actually never did so. If you plotted it through you would know what was coming. If something wasn't going to add up later you'd find out in the rough draft and address it.
As I was typing this out I saw Keii4ii's post. It is really important that you note what exactly is troubling you about your story. Rebooting without understanding why the story wasn't sitting well with you is recipe for accidentaly repeating said process. Write out questions like you were going to give yourself an interview. What was my original goal with this work? Why do I feel like this isn't working out? Etc.
No matter how obvious and straight forward the plot is in your head note it all down. It doesn't need to be detailed- a skeleton of an outline is fine. See what it looks like in a space that isn't your the vague goal points in your head.
Sure, for some comics that are more nebulous in story/arcs (if there are any) there really isn't a thing to plan towards. Expect you still are, because something is happening for each chapter (even if the effects of said happening doesn't stay for the next chapter). Even in these slice-of-life or newspaper strip style works you have ideas of moments that are going to play out. When you run out of ideas, or lose passion for the project, what do you want the work to end on?
