Did you know that tomatoes are not an annual? They are perennials that are grown like annuals. Research and experimentation have shown that tomato plants can live for years. However, it's been accepted that tomato plants will die off in the first frost, and that we must plant again from seed (or buy seedlings) the following spring.
Here's a way to combat that belief and practice: you can clone tomato plants. No, I don't mean messing with their DNA or adding fish genes. Tomato plants (and pepper plants too) are so easy to root from cuttings. I've done this in the spring, and wrote about it in this post - scroll down to the last paragraph about thinning seedlings. I've always hated to cut off and discard the overcrowded seedlings, then I learned that I don't have to discard them. Instead, I stick them in a glass of water and let them root, then plant them for new plants - double the crop!
So, if you live in an area where the tomato plants die off in the fall, take a few cuttings from your best plants before the first frost, and let them root in a glass of water. Then plant in a pot and keep them in a greenhouse or a sunny window for the winter. In the spring, you'll have healthy plants to transplant to the garden and you'll have a jump on the season.
You could keep this cycle going for years with the same plant.