Let´s be realistic. Having a better APR depends on many facts including your credit record and income.
Anyways, it is not bad always to Ask what they can do about it.
The last time I called Capital One, I received a temporary reduction of my APR for 7 months. This may not sound so great but at the end it is money to be saved.
Also if they do not have a better APR available they may offer something else like Cash Rewards for example.
Just take what they offer, every dollar saved count..