The Londoner, 17, was left out of the original squad whilst she struggled to balance training with A-level studies.
However, Smith quit college in March in order to focus full-time on her preparations for the London Olympics.
She is spending most of her time in Leeds at the weightlifting National Training Centre.
The World Youth Championships take place in Lima from 8-15 May.
"I am really pleased with Zoe's progress over the last six weeks," said performance director Fiona Lothian.
"Since moving her base she's made both technical changes and we've increased her training volume.
"She has settled into this new routine well and is now back to the form she showed at the European Youths in 2010 (where she won a silver medal)."
Smith competed in the 2009 Youth Championships in Thailand, finishing eighth and is aiming to better that this time around.
"This is my last chance to compete in this age group so I'm really hoping to show how much I've improved (since 2009)," said Smith.
"Peru sounds a pretty cool place to go so I hope we get a chance to see more than just the training and competition halls!"
The teenager turned 17 on 26 April, which brings with it another new challenge.
"I was away from home for my birthday for the first time which felt a bit weird, but my mum booked me a driving lesson in Leeds on the day itself, so driving is my next big ambition," she added.