If your Printcrete is just dirty and has no surface damage, the best you can hope for is a clean surface obtained using a pressure washer.
Remember there are pressure washers and there are pressure washers, you haven't stated the performance of yours. It may pay to hire a proper tool for half a day to get the best result.
Thompsons Ultra Waterseal would give you a surface less likely to stain, but wont make it any cleaner. Only the pressure of your washer will achieve this.