I've made some updates to the webSockets lib ws.js

Ahh, yes - that's definitely your issue.

With WIZnet, when you create the Websocket, I think it connects immediately - which might cause a delay which would stop everything getting uploaded correctly.

Even using a setTimeout would work:

var eth = require("WIZnet").connect();
eth.setIP({ ip : "192.168.0.10" });
var data = JSON.stringify([{
  topic: 'espruino',
  messages: ["199-hello\nldskjfds"]
}]);
var t = setInterval(function() {
  console.log("Write  should be done every 2 seconds");
  //ws.send(data);
}, 2000);
var WebSocket = require("ws");
var ws;

setTimeout(function() {
  ws = new WebSocket("192.168.0.6",{
    port: 8080,
    protocolVersion: 13,
    origin: 'Espruino',
    keepAlive: 30  // Ping Interval in seconds.
  });
  ws.on('open', function() {
    console.log("Connected to server");
    //Send message to server
    ws.send(data);
    console.log("Sent first time");
  });
  ws.on('message', function(msg) {
    console.log("MSG: " + msg);
  });
  ws.on('close', function() {
    console.log("Connection closed");
  });
}, 1000);