I'm quite confused as you seem to be answering yourself on theses sentences you wrote:
We are wondering if we should focus on our mobile apps or our website. Currently, our desktop traffic is significantly more compared to the mobile apps. We believe that in about an year, our mobile traffic will surpass the desktop traffic.
The data is telling you where to go, so it's a no brainer. Like Udhaya said, if you use responsive, you should be covered on both fronts. That's the minimum.
Best of lucks!