Requeening hive question

Checked my hive yesterday and notice there were very few eggs (one small cluster) and lots of drone caps. Hive was doing well the last time I checked but clearly not anymore. There still a sizable amount of workers but so I want to requeen since it seems like the current one isn't doing so well. Ive never requeened a hive with a still living queen and wasn't sure if it should kill the current queen the day I install the new one or if I should do it in advance so the hive knows it's not queen right.