It’s always an exciting time when your child is ready for a bigger bike! That being said, just over three months is a surprisingly short amount of time to have a kiddo outgrow a bike; were we able to help size your daughter for her new bike back in December?
To answer your question directly, REI does not have a trade-in program for bikes. There are many good options for re-selling bikes, including online marketplaces and local second-hand resale shops. In addition, many cities have local non-profits that match donated bikes to kids who need one.
Hope this helps!
At REI, we believe time outside is fundamental to a life well lived.