How do I upgrade just 'lein repl' to use Clojure 1.5?

    [bin]$ lein version
    Leiningen 2.0.0 on Java 1.7.0_15 Java HotSpot(TM) Client VM
    [bin]$ lein repl
    nREPL server started on port 41384
    REPL-y 0.1.9
    Clojure 1.4.0

I understand that Clojure is just a jar dependency, just need to find where lein's dependencies specified...

For a new project I would have specified Clojure 1.5 in defproject, but for REPL?