Do i need to consult my previous employer again?

I hav one doubt regarding my visa cap exemption tat is if i want to go for cap exempt with my unused visa which was stamped in 2008 April to 2010 September, do i need to consult my previous employer again? or can i proceed with other new employer? i didnt even utilised my visa once n its been expired too. so if its possible to extend my visa then i have to pay fee again to the previous employer? is there any time limit for to apply for cap exempt? am in confusion.

No need of Previous Employer, if U have Case Number/i797 Copy.

And Ur Petition is Approved in 2008, so this is the last year u r eligible for Cap-Exemption, So make it ASAP