Reconfigure GPS on Nike+

I recently purchased the Samsung Gear S2 with 4g capability. I love the watch and am super excited that I can go for a run without my phone and still stream music and use gps tracking. However, when I have taken the watch for runs without my phone, the mileage is off by quite a bit. I ran on a familiar course and found that it was about 0.25 miles behind (which makes it look like I'm running much slower than I am) when using the Nike+ App.

Has anyone else had a similar problem or have any idea of a way to re-calibrate it or help it to get a better read on me? I know that it can't be perfect, but I would like it to be just a little closer.

Thanks!