1999 Dodge Neon The leakage from AC Area

Air Conditioning problem
1999 Dodge Neon 4 cyl Automatic 111000 miles

Dodge neon, 1999, mileage 111,000. Hello, I fixed AC last year 2007 in summer time. It worked good. The shop put some freon. Actually I don;t remember what else they fixed. But this year 2008, got AC problem again of Leak. How can I find the leak of AC, or what part? Compressor or condenser. Do I have to replace every each part one by one, then check there is leak or not a few days after? That is a lot ofmoney to do it, How?Can I detect the leak from the AC?