You have to add some code into your onLogin script then, since the server calculates hp/mana automatically based on level and vocation.1. I am using account manager.
if getCreatureStorage(cid, 30001) == -1 then
setCreatureMaxMana(cid, 100)
doCreatureAddMana(cid, 100)
doCreatureSetStorage(cid, 30001, 1)
end