Yeah, I used to stay in bed on my bad days too. The only way I got out of it is to form habits/routines (exploiting that part of ASD). I would get up at the same time everyday, even on my days off (maybe lay in for an extra hour at most). This constant cycle broke me out of it and just became the norm.
But honestly, mental health sucks. Most of the time there isn't any point in getting out of bed, eating, keeping good hygiene, or even functioning. Even when I get up, I just find some other place in the house to vegetate. But hey, that works for me so maybe it could help you