Whether you will be able to repair a cracked beveled glass fireplace screen will depend on the extent of the crack, where on the screen it is located and your experience with similar tasks. If the crack is small, it might be managed efficiently and effectively, but if it's extensive, the measures you take might be undermined by the constant heating up of the fireplace, and a replacement might be a better option.
The decision to repair or replace a screen can also depend on whether the fireplace has one or several panes in the design. If your fireplace has several panes and there is only a crack on one of them, replacing the one pane might be best. However, if it’s a single pane and the crack is manageable, do-it-yourself repair is an option.
To repair a glass fireplace screen, first clean the glass thoroughly around the cracked area, letting it dry completely. This will make your work easier and help you avoid cuts.
Second, purchase a heat-resistant glass adhesive such as a high-temperature RTV (room-temperature vulcanizing) silicone that can resist temperatures as high as 600 degrees Fahrenheit. Any adhesive you find should dry clear. Follow the directions on the product for the proper amount to use in relation to the crack.
Next, affix a glass repair bridge over the cracked area using the tightening screws to apply an adequate amount of pressure while the adhesive dries. Again, follow all directions carefully.
The final step will be to remove any excess resin once the adhesive is fully dry using a razor or a glue removal product.
Keep in mind that, as with any repairs related to plumbing, heating, and air conditioning and ventilating, the materials involved channel or contain elements which, if used improperly, could cause problems in the future, so be sure carefully follow the directions of any repair materials you use.