what are your goals? can you talk us through the process you go through when you get demotivated?
for example, sometimes when i get demotivated, it goes like this: i really want to do better than ever before > i realise i still have the same weaknesses as i did a year ago, because im still the same artist OR > i decide thats impossible when bogged down by my earlier work in the series OR > i decide that, after drawing two pages, i dont actually understand my craft well enough and everything i make is too pedestrian / low brow / pretentious / boring / predictable / nonsensical / take your pick > i procrastinate and consider ending the series and becoming a gardener.
it could help you to work on a far shorter, for-fun project, or do some exercises in form and the like. these short projects can be simply exercise, which makes them lower pressure, and its way easier to get from start to end - which i think is a really important process to go through to keep on going with anything else.
exercises in form and process - setting challenges like "this month, im going to make a 4 page comic that tells a story with only images, no words" or "this week, im going to add a panel to this comic every day, based on how im feeling at the time, and see what the resulting comic says." look into people like scott mccloud, chrissy williams (over the line), and matt madden (99 ways to tell a story) for more examples and inspiration.