Ckeditor Replace and focus on last/ alternatte http://ckeditor.com/addon/autocorrect

sample.js

      CKEDITOR.on('instanceReady', function(ev) {

          var editor = ev.editor;
          editor.on('key', function (event) {
              
              setTimeout(function () {
                  var edata = editor.getData();

                  var replaced_text = edata.replace("#1", "one"); // you could also use a regex in the replace

                  editor.setData('', function () {
                      editor.insertHtml(replaced_text);
                  })
              }, 10);

          });

      });