Today I was asked by a chap called Angelo what he could do to continue losing weight.  He has successfully lost two stone through dietary changes and exercise but has now plateaued.  I suggested:
Cutting out all carbs in the evening i.e. dinner to be protein (fish, meat, beans|pulses)  and lots of non-starchy vegetables such as leafy greens, broccoli, peas, courgette etc.  You will probably have to make your protein portion a bit bigger than you normally have and make half your plate green veg to feel full (and also to give you lots of metabolism enhancing vitamins and minerals.)
At the gym start with a quick burst of cardio to get your heart rate up and then do plenty of weights to build up muscle.  (The more muscle you have the more calories you will burn even when you are sitting around doing nothing as maintaining muscle uses up much more energy than maintaining body fat.)