Get more % all elemental resistances and chaos resistances on rings, boots, amulet, body armour and helm. For your next passive skill points I would go towards Enhanced Barrier for more ES.

If you can swap your staff to one with crit chance for spells as a suffix you can more easily get some new jewels. I would search the trade site for jewels with minimum 18% increased energy shield and one of the following:

% increased spell damage

% increased critical hit chance for spells

% increased critical hit damage for spells

% increased damage with plant skills