All of the refined techs (like Refined Agriculture) are "infinite", they can be researched multiple times and give their benefit each time they are researched.

Not seeing Resoln in your empire list may be related to an issue that is fixed in the next patch where oyu can contact other factions form seeing their lands, but you wont be truely connected to them (so they wont show up in your faction list).

There is nothing saying it IS in fact repeatable, it should be obvious, and it should be easy to go seek how many of these I have already researched before, that's what I think anyways.

Sincerely
~ Kongdej

there's a "fix" coming that should make it more apparent that these techs can be researched multiple times