Need expert's advice, pjiang, 863211 please.

H1b, I-140 approved, H1b extened 3 year after 6 years based on I-140 approvel and still has 2 more years. Lost job this month and don't know if ex employer will withdraw H1b and 140 or not.

Now should I change immediately to a dependant H4 visa and change back to H1 when get a job (will I be able to change back to H1 again in this case ?)

or just try to find a job ASAP and transfer the H1b when get a job. 

Please advice.