If you want the picture to be updated go to insert tab, click on pictures, simply past the url of your image in the filename field but instead of pressing insert, chose (in the menu under insert) insert and link (or link to file. Both will work).
If you want the picture to be updated go to insert tab, click on pictures, simply past the url of your image in the filename field but instead of pressing insert, chose (in the menu under insert) insert and link (or link to file. Both will work).