Can you identify which classes work best and which are silent? If most of your classes are great it's unlikely that you are boring! How long have you been in China, and what nationality are you? Are you teaching a special subject (e.g. Business English), and what age are your students. Why do they want to learn English?

It is not reasonable to speak in generalisations, but I have found that some students in much more interested in learning grammar etc., and regard speaking as a "waste of time". I have spent considerable effort getting them to believe that the whole point of learning a language is to enable you to speak it! I suppose you could get them to debate topics such as "Learning grammar is more inportant than speaking the language"!

Have you tried showing 10 minute clips of videos and asking students to describe what they have seen, or predict what happens next - you can use all sorts for this, blockbusters, Wallace and Grommet, Mr. Bean etc.

Lyrics of pop songs in English are also useful. Try http://www.lyrics.com/ and http://www.absolutelyric.com/

Don't know if you've tried the IELTS-type speaking test - give each student
a topic on a piece of paper, they have one minute to make notes, then have to talk to their partner for 2 minutes about the topic. You do need to split the class up for this one, as there is nothing worse than listening to 10 people speak before it's your turn!

YOu might find some useful exercises here http://www.onestopenglish.com/tefl_skills/