Mortgage Due in 2016

It isn't likely that you can call in the whole amount of the mortgage ("accelerate" the mortgage) unless the borrower has violated some of its terms. 

If you simply would like to get all your money before 2016, you could always sell the "paper" to one of the many outfits that will pay you cash for the right to collect the rest of the money.  The problem is, though, that they won't offer you the full amount of the debt.  They usually need a steep discount to make the deal worthwhile, because they'll be waiting years before they receive all the money.

One other route might be to offer your borrower a discount -- in this case a more modest one -- for immediate payoff.   Sometimes, depending on the interest rates involved, it might even pay your borrower to obtain another loan elsewhere and pay off yours.