Unlike Smartforms which mostly use "new barcode technology" (refer to note 1557674), most sapscript forms uses the barcode fonts (code39/code93), which the printer need to be able to recognize, you need to contact the printer manufacturer (or visti their website) to install the fonts on to your printer.
Like the note mentions you can try changing the device type for your new laserjet printer in SAP to SAPWIN and see if it works (Tcode STAD, contact your BASIS administrator).
Also make sure the printer name has been changed to new printer name in tcodes OMJ3/OMJ4/OMJR