Increasing your mana helps two fold. As it gives you added defense and scales damage with archmage. So whatever you do, don’t take out archmage. The extra damage you get is hard to replace.
If I were you the next thing id try and go for are Time lost jewels and maxing out on passive stacking. They’re a good investment in terms of value/power you get out of them for the price. You want ones with large radius which run 300-600div depending on the stats. I have 1 with %increased max mana and one with curse aoe.
Personally I prefer a shrine scepter with one of the resists aura. It allows you to focus the rest of your gear on other stats such as item rarity (which I think makes a difference with drops) or chaos res (another defensive layer). This would require a lot of moving parts so could get expensive quick. But just something to consider moving forward.
Also additional mind runes. One doesn’t do much but 3 or 4 scaling with your other %max mana stats can start to add up.
And probably one of the more expensive things would be to upgrade your amulet. You have a really good one now, but if you were able to slot an additional T2+ flat max mana on it, that would help a lot.
Here’s my current build. 4.5k mana and max chaos res with 100+ item rarity. Just if you need some ideas.
https://poe.ninja/poe2/profile/j3rrin-5529/character/pikachu_
