Need Help : H1B Amendment / Extension / Cap-Exempt

[Anurag9]

I have a valid H1B work permit raised for customer X which is valid till Sep 30, 2016 (I havent utilised yet).
Currently I am outside of US and working for a new Customer and planning for travel.

Could you guide me on this to proceed further - since currently i'm at offshore
- whether to apply only Amendment (if so, when to raise the extension) ?
- whether to apply both Amendment and Extension at the same time ?
- or go for the Cap-Exempt process (if so, do I have to take the visa interview again) ?

I am in a very tight situation, any help would be highly appreciated.

Thanks in advance.