How can I make over a steep ceiling in a log cabin?

The biggest challenge is getting up there and working safely.

Borrowing or renting scaffolding would be the safest.

Since you don’t mention why it needs to be re-done, I would install two layers of polystyrene foam insulation that comes in 4’c8’ sheets and you can add at least R-10 to your cabin.

You’ll need the correct adhesive and nails that have plastic washers on them to keep from pulling through. I would pre-paint them on the floor before installing them. And then touch up the paint after installation.

What is wrong with the ceilings and walls that needs 'redoing'?

What's an N wall?

Having been in 100s of log cabins, most common is white washing to make the loft brighter.... personally I did a dormer to open up the ceiling and improve air flow. Here's some inspiration.... https://www.google.com/search?hs=8wk&sxsrf=ACYBGNQYmz5BLAtLtSf7DgzJ1wZN_3NPNQ:1573530058531&q=pictures+of+remodeled+log+cabin+loft+ceiling+remodels&tbm=isch&source=univ&client=opera&sa=X&ved=2ahUKEwj-lrqh4OPlAhUKnZ4KHVNmCT4QsAR6BAgHEAE&biw=884&bih=417

We paid a contractor to sand and seal our circa 1973 water stained cedar log walls and ceilings in our vaulted great room. The room looks like new.

Originally- we attempted to do the project ourselves. It is extremely labor-intensive and messy. We got a price from the contractor and it was well worth or 3 to 4 days worth of contracted workers work to get the job done quickly efficiently in a professional manner.