H1B Cap exempt

I got my visa for 2008-2011, but never travelled on that.

If now I plan to visit what needs to be done to use the H1B cap.

Approval was 2008-2011
Got H1 stamped in 2010

Never travelled to US.

Planning to reuse H1B cap

IMO, your H-1 cap-exempt period expired in 2014 (6 years from original H-1B approval date).

However, there are others who have said 6 year period starts from original H-1B expiration date. Using that, you have until 2017 to file a cap-exempt petition.

Still, there are others who have mentioned that it can be done even after 6 years: http://www.murthy.com/2015/11/23/h1b-remainder-approvals-even-after-long-absence-from-u-s/