No need to heat it. Pop off the pearl, and insert a needle into the pearl hole.
Then just squeeze the old insert out. If you're not planning to use it anymore, that is...
PS: When you reglue the new insert, keep rotating the bezel for the next hour or so. It's not nice if your bezel gets stuck. Sometimes, when you put too much glue, the insert edges get attached to the crystal.
And don't use superglue (which can damage the insert surface), just standard paper glue will be fine.