I don't use reading plans much, so I'm hoping someone might tell me that my suggestion is already possible. If it is, I'll use reading plans much more!
Here's what I want to do. When I've missed readings, I want to be able to adjust a reading plan so that unread portion is spread between today and the existing finish date.
So, if I'm reading three chapters of the Bible a day, and want to finish by the end of the year, but have missed several days reading. Rather than be consistently behind, I want to be able to adjust the plan so that I'm perhaps reading four chapters a day, so I can still finish by the end of the year.
Does that make sense?