In most cases, if nothing else is changed except the addition of images for the List of Images by Pointer, it is possible to download the updated VisiLogic file to the PLC without stopping or rebooting the PLC.
However, be cautious. Things can go wrong anytime you download a program update to a PLC and if it is running a mission critical application, you might want to think through the ramifications carefully in the event the PLC must be stopped for some reason.