Going backwards with Invisalign aligners

I recently completed 34 trays of Invisalign treatment. My orthodontist is satisfied with the result of my lower teeth, however he feels that the bite of my upper teeth has not moved sufficiently. He has advised me to go backwards in my tray (i.e. 2 weeks of 33, 2 weeks 32 etc) and now has me changing trays once a week. Is this standard practice? Will it reverse the movement of my teeth thus far?