10 year visitor visa renewal

[ds1104]

My in-laws' 10 year B2 visitor visa expires in March 2012. Is there a process to renew this visa? Or do they have to apply for a brand new B2 visa and start afresh?
P.S. I am referring to renewing the B2 visa beyond the 10 year limit and NOT "extension of stay in the US".
Thanks.

[kabkaba]

It will be the same as before. There is no separate renewal.