...if mod is added to a game where the science packs are already researched.

for _,force in pairs(game.forces) do
  force.recipes["artillery-combinator"].enabled = force.technologies["artillery"].researched
end

This is how "Artillery Combinator" unlocks its recipe if the tech is already researched. Just put it in migrations/modnameOrSomething_1.1.6.lua and it will run once and fix it.

I unlocked my recipes with the command

/c for i, v in pairs(game.player.force.recipes) do if string.find(v.name, 'science%-ore%-to%-science') then v.enabled = true end end

Hmm, interesting. Thanks for pointing this out I will look into it.

I added a migrations file that should resolve this problem. Thanks for pointing me in the right direction.