Scratching on the couch?

My cat always likes to stretch and jump and sharpen her claws on our leather couch. I tell her no and make her go use the scratching post but she always does it again. We tried using a spray for making a cat not want to go to a place so she would stop scratching but she still keeps scratching . like i know they are suppose to do that but i want her to use her scratching post WHAT TO DO??