You have also mentioned that you took a reading on a dual T5HO with a reading around 170ish @ 12" which is I think is about right. I am getting 300ish on my frag tank 4x TEC T5HO @ 12" considering my bulbs are more than a year old.
I think your LED emitters are not giving you it's full potential anymore. What I would do is maybe go to a buddy that has LED fixtures and compare his reading to yours using the same PAR meter.