This has happened to many of us. Your oven is hot. You have a beautifully crafted pizza ready to cook. You are minutes away from food time. You give your peel one last shake, but only part of the pizza moves.
If you can't get it unstuck with shaking alone (and this typically isn't enough if you have a leak), you will need to try to carefully lift the stuck spot. Using two spatulas, and even a third hand, if available, can help out greatly. I recommend easing a large plastic or metal spatula to start with. While it may have limited reach, a larger spatula will allow you to lift the pizza without stretching it too much or disrupting your toppings. Then, using a second, smaller, rubber or silicone spatula, shove some flour or corneal under the first spatula. If you see a sauce leak, I recommend using flour. Think about it this way: if you spilled oil on your driveway, you would probably try to soak it up with kitty litter rather than tennis balls. If the stuck spot is large enough, you will need to repeat this process from another direction. As you work to unstick the pizza, keep shaking, and work the pizza towards the edge of the peel. If you get the pizza unstuck, try to keep shaking it until you are sliding it into the oven. If you can't get it to stay unstuck and all else fails, get your large spatula(s) under the sticky spots, place the leading edge of the pizza on the baking surface in the oven, and shimmy/shove the pizza off of the peel. Only try this if the oven temperature is low enough that you can do this safely. If you are using your standard home oven, you should be fine, especially if you use something to protect your hands. It also helps to have another person to open the oven and help you out with another spatula if needed. You might end up with a pizza that is shaped like Texas or a donut, but it probably won't be a total loss, and you will probably get better with time.
While I am at it, I will share some prevention tips, specific to your situation, that I have learned, but haven't found elsewhere. You can find a few more here, but it sounds like you're already familiar with those tips:
- If you see a weak spot in your dough once you've stretched it out, you can preempt it with extra flour underneath it before you start adding toppings.
- If feasible, you can also try using little or no sauce on that spot.
- If you are making pizza, there is a good chance that you have another human around, waiting to consume it. Conscript that person to either help with toppings, or to shake the peel at regular intervals. This can help you get to the oven faster, giving your pizza less time to stick. If you use that person as a shaker, you will know as soon as your pizza starts sticking. Try to handle any adhesion as soon as it happens, when there aren't as many toppings to disrupt.