Runscape warpriest armour

So well, tier 2 just opened today and I ran to buy the armour, lets say I got the Defence level 75 bonuses from the cuirass and the grieves.

But, my boots and my guantelets stood at level 55, since I bought them with 70 Defence.

Level 55 Bonus for boots and guantelets: 31 Armour 120 HP
Level 75 Bonus for boots and guantelets: 56 Armour 180 GP <— ( I should have this bonuses but I do not)

Do I have to destroy my boots and buy new ones? Or does it auto-upgrade? Hope you can help me!