If the NI becomes useless in 1650, it seems like you should get an event that removes it for free, blocks it from being repicked (for the AI), so you can take another event.
Either that or give it some more bonuses, so that when you lose the war-dec bonus it's still worth holding on to.
cb_crusade = {
mutual = yes
badboy_factor = 0.25
prestige_factor = 1.5
peace_cost_factor = 0.5
prerequisites = {
OR = {
religion_group = christian
religion_group = muslim
}
NOT = { religion_group = THIS }
OR = {
government = imperial_government
defender_of_faith = yes
neighbour = THIS
THIS = { is_crusade_target = yes }
---->>> [B][U]idea = deus_vult # Actually "Unam Sanctam" <<<---[/U][/B]
idea = divine_supremacy
}
NOT = { year = 1650 }
}
allowed_provinces = {
always = yes
}
po_annex = yes
po_demand_provinces = yes
country_desc = ALL_INFIDELS
prov_desc = ALL_PROVS
war_name = CRUSADE_WAR_NAME
}