Regarding rocky planets in our solar system:
Sure, you just have to go check out enough of the rocks on the surface.
Regarding exoplanets, and likely our own gas giants:
There are no methods by which we could determine such a thing with anything near today's technology. Maybe someday in the distant future we might be able to measure the magnetic field of the planet directly (with Zeeman Splitting or something), and might notice if we happened to observe a reversal... but that's incredibly unlikely.
Theoretically that information might somehow be encoded in the circumplanetary environment... e.g. maybe there would be some signature encoded into a debris-disk / ring system; but the prospect of that both happening and being observable is pretty out there.