Painters alcholol(can't remember the proper name, denatured alcholol I think) will remove the adhesives without hurting the lexan according to one of the more popular aircraft lexam window makers
I had a airplane that had aircraft paint overspray on the lexan windows from that company and that is what they recommned to remove the over spray followed up with a good brand lexan window cleaner
BTW, Pledge furnisher polish works excellent as a lexan window cleaner, many small aicraft owners swear by it
rub it on with a clean, soft cotton cloth and rub while it drys, it even hides small scratches while flyiing into the sun in the morning or evening