Hi there and welcome. Well, I'm the queen of plateaus and I've learned a couple of things. First is DON'T GIVE UP, it can't last forever (my longest was 12 weeks of no loss while on plan before my body agreed to co-operate again).
I belong to Weight Watchers and was provided with a sheet to help combat plateaus. Here's a few highlights:
1. Confuse your body - many times when we've been at this for a long time we tend to eat the same foods at the same times because we become comfortable with the routine and if it's worked in the past we want to use a tried and true method. The problem is that your body catches on and adjusts itself to the routine also, so you have to confuse it by changing the makeup of your meals. For example, if you've been having a carb breakfast such as fibre cereal, skim milk and fruit, and a protein based meal in the afternoon/evening, switch them around and have your protein in the morning (mmm, eggs) and eat your carbs later in the day such as a nice caesar salad with lots of crisp romaine, fat-free dressing (cut the croutons and bacon bits), and whole-wheat garlic toast.
2. If you've been eating 3 meals a day, eat 5-6 times a day (smaller portions naturally).
3. Increase your water intake.
4. Boost your metabolism by moving more (needn't be much - i.e. adding two 15 minute daily walks to your regular exercise routine).
I repeat, DON'T GIVE UP! You may not be losing, but try to think of it as maintenance training
and believe me, when the damn finally breaks it usually does with a really nice loss that gives you a great boost! Good luck.