Notes:
For each ReUp, the amount of XP needed to level up grows quadratically (non linear). Because of this, level 70 (& not 50) is the approximate XP halfway point for all ReUps (& Wings)
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At level 50 you are ¼ through the ReUp (in terms of XP) and at level 85 you are ¾.
As a quick heuristic, you will reach percent of your ReUp at level: