When going into the Hue app to discover newly connected lights, the text at the top of the page says the following:
"Bulb Discovery Started!
Let's discover your bulbs. If you don't see any bulbs listed or have recently added a bulb, click the "Refresh Bulb Discovery" Button below. Once you have bulbs listed, select the bulbs you'd like to add. Click Done or Find Groups if you want to add any Groups / Rooms of Bulbs."
There is no "Refresh Bulb Discovery" button though.