I think there's always a way, it just depends on how much time there is
It also depends on the definition of responsive. A simple approach: don't use any fixed sizes for any graphical elements, make every single position and size proportional to ofGetWidth() and/or ofGetHeight().
One step further is to detect if the screen is landscape or portrait, and change the layout accordingly.
A more advanced approach, with variable number of columns and the ability to zoom in and out, you might have to code yourself (unless someone knows of a c++ library or addon that does this). http://doc.qt.io/qt-4.8/scalability.html lists some things to consider.