User blog comment:Xilinoc/Ch. 604 - REVITALIZE/@comment-24384892-20141106164827/@comment-3219912-20141110232245

I mean if the Captains, Lieutenants, and Ichigo could gain a significant power improvement between the 1st and 2nd invasion, then it's entirely possible that Uyru could have learned Vollständig and gained more power in that time period as well.