vim-fireplace is much improved. I had been using a heavily hacked version matched to my own preferences for years but recently upgraded.

What you really want is just to run

    lein repl 

in your repository and then fire up another terminal and edit code with Vim. Then you should send whole top-level forms to the repl with :Eval from Vim and it should just work. You can then test them in the repl. (I alias C-c C-c to :Eval (:no <C-c><C-c> :Eval<cr>) because I'm used to the old vim-slime)

And it should all work automatically. With the new versions of vim-fireplace it does just work automatically.

I'll write a 'process-data function in Vim, send it with :Eval, and then test it in the repl with (process-data {:some "data", :more "other data"}) and it all just works. There's a little reading up on namespaces necessary once your projects get complicated, but it works on a bare repl right out of the box, too.