Yes... you can cut the tops off and re-plant them. If the bottom part is starting to look leggy, then you can get rid of that and put the top in it's place. When you say side shoots, do you mean that there is no foliage on the sides, or that its not growing sideways?
There is plenty of foliage on the plants - all the way up the one 'main' stem... I just wondered if, once the top had been taken off (and of course, replanted... great tip!), side 'branches' would start to grow, making a bushier plant...