Hi, you say units so assume double glazed, normally the lead is also on the inside, so the job would require units to be split etc etc, to give a rough costing you should be able to buy new units for around �25-�30 per sq meter (have a ring around some trade places) going back to can it be removed and cleaned, yes, successfully depends on how much effort you want to put into it, remember if they are double glazed units you will need to get the spacer and sealant off without breaking glass and pay to get resealed.
good luck