Boil two cups of water
Add peels of lemon, orange, and/or tangerine (about one cup).
Let it simmer for around 20 minutes, remove it from heat, and let it cool.
Pour the solution into a spray bottle. Add two teaspoons of lemon juice and a squirt of lemon-scented dish soap.
Shake and spray on furniture, walls, or parts of your house you want your cat to avoid.