If you do use glue to repair the dome, be sure to allow the adhesive to fully cure before reassembling your MBP. Every adhesive I'm familiar with that adheres to silicone will release volatiles during the curing process.
Usually this isn't an issue, but in the warm, confined space of the MBP, they could attack other parts. Follow the instructions for your adhesive and double (or even triple) the curing time, just to be sure.