I have a small cut on the passenger seet.
To reapair it will probably cost alot. Its not a deep cut so I thought that maybe there is something that I can use to stop it to become bigger...

 

May not be as expensive as you may think. I had the same problem with my previous car and at a local shop it cost a little less than $100. Otherwise, I would call a upholstery shop and ask for there opinion on how to prevent it from getting any worse.