With my old glass vivariums, which I use for quaranteen, I covered the sides with this B&Q Radiator Reflective Foil - 500mm x 5m, 0000003765739
I also have an old viv (similar to the exo with the mesh lid) where I used a spare piece of melamine to cover the top and stop all the heat escaping through the roof, so to speak.
I stopped using incandescent bulbs as a heat source a long time ago but I used them in conjunction with a low wattage heat-mat to keep temperatures right. You could try upping the bulb to 150 watts, but an additional heatmat may be a more economical solution in addition to the insulation fixes.

P.S. - adding a rocky area directly under the lamp could also help to store/maximise the heat in the viv