Got US B1/B2 for 3 months, need extension

[biswasbn]

I am a PhD student in Computer Science from Lucknow India. I was planning to attend academic conference in USA from 9th to 13th August. There were no dates for interview in New Delhi during July, so I chose Kolkata(also my hometown). Officer gave Section 221(g), case held for 2 months. Got (B1/B2) visa this week - Single entry till Dec 2017 only.

I have another academic conference in USA in Jan 2018.

How do I go for a successful interview and visa renewal now? Or can I do without an interview?

[jnk]

There is no such process is called visa renewal. You may be eligible for interview waiver program.

Please read the eligibility at,

https://www.immihelp.com/us-visa-interview-waiver-visa-renewal/

If you are not eligible for interview waiver program then you have to go in person and explain the situation you had in your previous visa interview. Informed that you missed the conference last time after that you didn't visit US. In that case possibility of visa approval will likely to be high. But you never know.