First, I think you should go back to China to defense your Ph.D. degree. Then if possible, you can apply for a post-Doc. in your current boss in USA. If he or she does not have money, you can apply for post-Doc. positions anywhere in USA right now and apply for as many as you can since it is much easy to get a post-doc. position if you are in this country. If you get this chance, you can apply for J1 visa again. Please notice this suggestion depends on my friend's experience. He has very similar experience as yours. He worried whether he could get the J1 visa again after he came back to China. In fact, even though he was accepted by a small University as a post-Doc., he got his second J1 visa easily. I hope this helps you. Good luck.