Stop buying those stupid sisal rope scratching posts. What happens when you cut a rope? It breaks, the thing is fucked. Sound familiar?
Get a scratching post made out of woven sisal. It will cost 40 dollars but last as long as like 10000 rope posts
You’re welcome for this knowledge 
Can’t you rewrap them?
Why keep buying ropes that quickly get torn when you could have a woven matc that lasts years