Renewing passport

[Cori21]

If your 14 year old has significantly changed in appearance since getting their passport at aged 12, can you renew it, even though they have only had it 2 years? They had to do a double take at the airport last year even and I don't want and issues next time.

You can renew whenever you want.

Yeah, you can renew it whenever, just maybe pay the bigger fee (I'm not sure about that since you're renewing because of your own wish, not because it has expired). You сan take the picture at home as well, just make sure it's cropped according to the specifications https://passport-photo-software.com/passport-photo-guidelines-uk.php

What reason would I give? Is there a list of reasons to select when renewing eg lost etc?

Yes and you can say it was lost, I think.