I had a similar problem on one of my bows, where the glass came off on the belly side...
I heated the epoxy with a small electric oven to make sure that it was enough thin so I could use it to glue the glass back on. I used a syringe to inject the epoxy under the glass...
After all the gaps were filled completely I applied some pressure with a few c clamps...
The next day I sanded off the excess glue, applied the finish and the limb was almost like new...
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Andy