L.A.
My son did this in his preschool years. Instead of fighting it, I would ptake him in his pjs, pack a bag with clothes and off we would go. Once we got to where we were going, he would decide that he did want clothes and then there was no battle with the dressing.
Try just saying okay and see how long till she decides to change. It's a social convention and not a health issue, so letting it go and putting the ball in her court may change things up enough to put an end to this dynamic.
For night time, it may be weird to you, but there is no harm with her sleeping in her clothes. Or maybe she could pick out some sleep outfit so it becomes her idea.