I posted the problem a few days ago (attached below) and pjiang helped me.
Now the lawyer gave three choices.
1. Travel abroad and re-enter.
2. File an extension of status petition before I-94 expires;
3. Attempt to schedule an appointment at CBP for I-94 correction.
It will be the easiest for the 3rd one if it works. But the lawyer is not sure it they have this service or not. Anyone knows about this?
If the 3rd one does not work, we have to reapply the h1 extension. We have to pay the application and pp fee ourselves but it is Ok. The problem is that is it weird to apply one more time right after it was approved. Any chance it is not approved?
Finally the 1st choice, we have to apply for visa stamp in order to get new I-94, right? Can NOT go abroad (e.g., Canada) without applying visa and get new I-94, right?
Thank you very much.
==================================
LG的 H1 延期批准时，人在中国，他回来入境时 I-94 的有效期是 H-1 延期批准前的有效期。这样 H-1 延期批准上的 I-94 是不是就无效了，因为这个号码已经在出境时上交了。现在的问题是：
这个 H-1 延期是否有效？要重新申请 H-1 延期吗？
还是申请延期 I-94 （入境时给的那张）? 如何申请？可以去当地机场海关吗？ 还是要寄到 移民局？
另外，他将在第一个 H-1 过期前半个月去加拿大，可以在回来时在机场入关时，要求把 I-94 延期到新 H-1 有效期吗？
非常感谢。