You did not say how long it was refinanced for or the month when you refinanced.
Did you refinance with an amount of $120,000. Is the current APR 5.25%
I'll give you the formula you can use to calculate this since I don't know the above figures.
N = ln [ ( P+E) / (abs( rL - (P+E)) )] / [ln( 1 + r)]
P = Current Payment
E= Additional Principle Payment
r = monthly interst rate
ln is the natural logarithm
abs is the absolute value
N = the number of months to pay off the loan
Just simply substitute in your data , and you will get the figure you need.