Most cats have a preference for a particular type of scratching post. Some like wood or carpet, and many enjoy sisal rope. Unfortunately, the rope wears out after several months of use, and it can be expensive to keep buying new scratching posts. You may be able to save some money by simply replacing the sisal rope on your existing scratching post. It only takes a few simple tools and some patience to make that sisal post as good as new.
Check the scratching post to see how the sisal rope is attached, as you will not be able to replace it if it is glued. If it is attached with staples or nails, you can easily remove them and unwind the rope. If it is glued, it's nearly impossible to pry off all of the rope.
Remove the top staple or nail with the pliers and unwind the existing sisal rope. You can roll it into a ball as you go for ease of handling. When you have balled up all of the rope, remove the bottom nail or staple to detach it from the scratching post.
Cut a piece of the old sisal rope before you dispose of it so you can use it as a guide when you buy new rope. Sisal rope comes in various sizes. Bring the old piece to the hardware store so you can compare it and buy the same size. Purchase two rolls to make sure you will have enough. If you have too much, you can always use it the next time the rope needs replacing.
Nail one end of the new spool of sisal at the bottom of the post. Make sure you drive the nail all the way in so its head doesn't protrude. Otherwise it might catch on the cat's paw and cause an injury.
Wrap the rope around the post, working your way to the top. After every five rows, stop and push the rope coils down to prevent gaps. Make sure you pack the coils as tightly as possible. If one roll of sisal is not enough to cover the entire post, simply nail the end of the rope into the scratching post when it ends. Then take the new roll, nail one end next to the end of the old roll, and continue winding.
Once you reach the top of the post, cut the rope and use another nail to secure the top to the post. Drive the nail in as far as possible so the head won't protrude and possibly cause injury to your cat.
Rather than replacing the sisal on your cat's scratching post, you may want to purchase a post with easily replaceable parts. For example, Doctors Foster and Smith sells cat furniture made with easily detachable and replaceable posts.