Can you give a 1-time topfeed of regular pH'd and let that drain out, then resume with normal dose? or just circulate for X hours with autopot system -- not sure exactly how those work as far as timing and such. you get the idea, i'm sure.
~10-20% runoff should drop EC in half or so. Could resume with a 75% reservoir concentration?
If you have an EC pen, this will be much easier... just get runoff where oyu want, and resume regular feed.