There is no need to use do here.
Even if I play it once in a while, (then) I will go back to bridge.
Even if I played it once in a while, (then) I would go back to bridge.
I believe you can use these two version.
The then is an option.
However, I cannot really tell you which one you should use...
I guess sentence 1 is more suitable, because you have already played poker.