You can use Ctrl + G to enter Job control mode, there you can interrupt the running job (e.g. with i 1) and connect to it back.
iex(5)> IO.read :all
1111
User switch command
--> j
1* {erlang,apply,[#Fun<Elixir.IEx.CLI.1.121285560>,[]]}
--> i 1
--> c 1
{:error, :interrupted}
iex(6)>
