gdogfunkanswered grow question 5 years ago I think your humidity levels are fine for now.
If you really want to bring it up, you can place a bowl of water or a place a damp towel hanging in the tent and continue to dampen it every few days as it dries out. I really suggest fabric pots over plastic, as well. You will find the plants will get larger and more robust and you will find the humidity naturally increasing due to the wet fabric holding moisture until it begins to dry out. I hope this helps!