Are you on hormonal birth control? Some types of birth control promote hair growth while others reduce it. Here's a great source (in French) about the topic:
Martin Winckler's webiste.
As far as I know, electrolysis is the only permanent method, although all methods that pluck out the bulb (plucking, waxing, threading) will cause the hair to get thinner overtime. I like threading for its eco-friendliness and the very minimalist material it requires.