Am I eligible for H1B cap exemption?

I have an unused H1B visa, stamped only for One year expiring on 31-Dec-2015. The "I-797B, Notice of Action", which I believe is my H1B petition approval notice shows validity from 10/03/2014 to 12/31/2015. I am unaware of the visa process and so I am requesting some help here for further actions.
1. How do I get my H1B extended?
2. Should my employer again file for H1B with a new petition?
3. Do I have to go through the process of Lottery ? And if selected go for stamping again?

Please provide me with suggestions so that I can request my employer accordingly.

Thanks in advance,