Yes, after you reach each level, that amount of XP gets deducted and you need to earn for the next level again. To go from explorer to gold, it means you have to earn 280xp, 100xp to get to silver plus another 180xp to get to gold. Getting to platinum is then another 300xp.
That's a lot of XP, but once you're at platinum it takes 'only' 300xp to renew, not 580xp