Best way to repair Neoprene gloves
I've got some wetsuit glue, and the join is really tough.  Just be sure to use it on clean, dry material,follow the instructions carefully (it's a bit like patch cement), and allow it to set for plenty of time before use.  Sadly, you can probably reckon on a nearby failure before too long, as the stress is moved to a different place.

I recommend keeping the glue in the freezer, sealed in a bag -- it keeps longer that way, so you should get another few uses out of it.