H1 to H4 to H1 on 7th year extension

[sriniid]

Hi, My wife is finishing her 7th year H1B extension. Her I140 is approved.  She wants to resign and convert to H4. Once she converts to H4 the employer says he cannot maintain I140 and will withdraw it. Can she convert to H4 and then back to H1 ? Will she have to wait for 1 year before she can convert back to H1 ?

 

All replies appreciated.

 

Thanks.