H1-B Visa extension without travelling to US even once ?

Hello,my Visa(H1-B) would be expiring in July,2013.I have still not travelled. Is it necessary to travel to US before applying for extension?If yes, how many days before? Can I renew my Visa here from India??

You can file for extension even w/o travelling to US. Your employer will have to show a job for you in US, and USCIS can come back to ask why they should approve when you haven’t utilized the previous term. The valid reasons include market conditions, global slowdown etc.