Weve had a lot of cats growing up, and from my experience, the only way to keep a cat inside is to never let it out.
Little Bisk is totally an indoor cat, since we live in the city (though occasionally escapes into the hallway of our apartment building)
A siamese i had about 6 years ago was let outside for one day, and we couldnt keep her in after that, she always found a way out.
On the other hand, my mothers two cats were never allowed out, and now they run away every time the door opens, they are afraid to go outside.