Before you decide to apply extra income to your mortgage or refinance to a shorter term, here are a few things to think about:
Are you taking full advantage of your employers company match on your workplace retirement plan?
Do you have other debt?
How about your emergency fund? Would you have the saving to get you through an un-expected expense or loss of income?
With the tax advantaged treatment of mortgage interest that you may decide that the effective interest rate is low enough that you can obtain a higher return somewhere else.