My dad fixed his (now mine) by first roughing up the glass so the epoxy could grip. My dad was a very clean, tidy man that would fix things to look better than new, but this was a bit of a rough job (excuse the pun). I was too young when he did it, but looking at the finished product I'd say he must have tried a few times with just gluing before he went at it with a grinder or sanding paper or something. But then it lasted for at least 20 years if not 30 (I'm 39 and remember it for every as it is now).

If you want to spend money, go to a glass splashback manufacturer (for kitchens) and get them to make you a new window with holes exactly where you want them. You can even select your own colour (or "color") if you fancy that.