Will increasing weights increase the amount of muscle?

I've been working out with weights for almost two years.  At one point I was at 21% body fat which, for my age, is good.  Then I quit doing cardio and I gained weight and haven't had an analysis done since then.  Since I've been keeping up with the weights I'm thinking that I've increased my body fat while maintaining my muscle mass.  Here is my question......If I increase the amount of weight I use will that increase my muscle mass?   I don't want to do that I just want to loose fat.  Should I maintain the weights at the level I'm currently doing to maintain the muscle or do I need to increase the weights to maintain the muscle.  I know I'll have to increase cardio to decrease the body fat.

Mmm, it probably won't since you've got an intermediate training age of 2+ years - as long as you maintain a calorie deficit and do strength training the best your body can do is to hang on to what you've already got.

 You'll probably gain strength due to increased neural efficiency, even if you don't gain appreciable amounts of muscle mass. If you keep up the strength training that is - if you stop lifting weights you run the risk of losing equal amounts of fat and muscle.

 If you can increase the weight you use, go ahead - as long as you're in a calorie deficit anyway. Though you might want to read Sexy Female Training by Chad Waterbury for one trainer's perspective on how you should train for a certain look - his examples might not be what you're after in terms of your own look, but if you follow along with his logic you can see what you'd want to emphasise in your own program.

(edited to add:) Also, read The Hierarchy of Fat Loss by Cosgrove - you should definitely keep the strength training in your mix; it's way more effective than straight cardio for fat loss.

Thanks for the links.  I've scanned them and think they might be helpful.   Now if I can only work out and get taller than 5' 3".

I've heard of a process where they break your legs and put separating bars on each side of the bone as it heals. Every few days they adjust the bars so the distance between the two borken bones increases. As the new bone heals into place you end up with longer legs and thus more height. 
If you ask me, 5'3" is mighty fine :}