SSL redirection rule with regular expresion

Sure you can do that. Make sure this iRule is on your HTTP virtual and not your HTTPS virtual or else you'll get into a circular loop.

when HTTP_REQUEST {
  switch -glob [HTTP::uri] {
    "/*/morethings" {
      HTTP::redirect "https://[HTTP::host][HTTP::uri]"
    }
  }
}

This will match the following

http://www.foo.com/onething/morethings

http://www.foo.com/onething/twothing/morethings

...

It will not match this:

http://www.foo.com/morethings

Now, if you just want to make sure that your URI ends with "/morethings" you can do something simple like this:

when HTTP_REQUEST {
  if { [HTTP::uri] ends_with "/morethings" } {
    HTTP::redirect "https://[HTTP::host][HTTP::uri]"
  }
}

Hopefully this will get you going in the right direction.

-Joe