The Clojure REPL in this workshop does not save any code you write once you leave a page, or if you refresh the page.
repl.it is a Cloud development environment. Create a free account to save the code you write to solve challenges from the ClojureBridge London workshop.
repl.it also lets you share your code with other students (or anyone else) via a simple repl.it link. The link presents your code in a REPL so those you share with can easily run your code and experiment with it.