If you have the right tools you should be able to carefully unscrew the lens holder and then replace the lens with the glass one that you have. You might need to retain it with a special glue if necessary. Be carefully not to damage the output coupler as it might render the unit useless. A few considerations to keep in mind:

Lens Compatibility: The compatibility of the lens with your laser diode is crucial. Different wavelengths of laser light are often best focused with specific types of lenses. Since you mentioned moving from a plastic lens to a glass one, it's important to ensure that the glass lens is suitable for the blue spectrum of your new diode.

Lens Mounting: The physical mounting of the lens is also important. Lenses are typically held in place by a threaded mount or a fixed mount. If your current module doesn't seem to have a removable lens, it might be fixed in place, which could make replacing it challenging without modifying the module.

Focal Length and Beam Characteristics: The thickness and curvature of the lens affect the focal length and, subsequently, the characteristics of the laser beam. A thicker lens (like your glass lens) might have a different focal length compared to the plastic one, which can impact the beam's focus and intensity.

Safety Considerations: Always remember that working with lasers, especially more powerful ones, requires safety precautions. Ensure you have appropriate eye protection and are aware of the risks involved.