Larva of some species commonly wander far and wide to pupate, and often do so in whatever handy place they find. To use you Monarch for an example, in Hawaii they seldom pupate on their Calotropis gigantea host plant. Most often you find their chrysalis on rock walls, chain link fences, etc at great distances from the larval host.

No need to move it unless you are worried about damaging it while harvesting your tomatoes. The elements won't bother it.

Larry

I am rearing Monarchs indoors, and most of the cats pupate on the paper towel taped to the lid of their container (then I move the paper towel to an aquarium tank, where they will eventually eclose). But a couple decided they didn't want to crawl to the top and pupated right on a milkweed leaf. I just waited 24 hours and then trimmed the leaf and taped the leaf to the top of the container along with the other chrysalides. This worked great. You can cut off the leaf and bring it inside if you'd like to watch the butterfly eclose, otherwise, as Larry said, I would leave it alone.