As the pool is going to be closed within a week, I'd say let it be (unless the 'low salt' light is on). This includes the presumption that you will be draining some water prior to closing, if you aren't going to lower the water - add some salt.
My thinking is that it would be a 'waste' ( ), to add more salt when you are going to dump some of it out w/i a week - if the unit is only running 5 hrs/ day, at a 10% output, the cell is only running 30 min/ day for 5 or 6 days. I would rather save that salt for the spring when it will be used all season (I know that a larger amt will be needed in the spring to compensate for the unsalinized water which brings the pool back up to 'operational level', but why 'waste' the salt now?)
Nice sharing a thread with y'all again!