Before you go back to China,
1.ask them to write a letter says you are taking a leave without pay.
2. Another letter state as of current date, u r working for them. (include job title/duty and salary rate)
3.use these two letter, plus your last two pay stubs,
plus your H1b approve letter.
4. don't turn in your i94 when leaveing usa
you should be able to get a visa stamp from US consulate overseas. which means u r using the same h1b visa u r using now. not a new h1b.
this 3 month can be recaptured for yoru H1b 6 years timeline in the future, but the recapture process is complicat.