Matt said:

After harvesting my pumpkins, would it be a good idea to plant
something in the late fall, or early next spring to help give the soil
something back (without taking away what the pumpkins usually use up)
before I plant pumpkins next year? If so, what would be good to
plant?

Hairy vetch or winter rye are usually recommended as fall/winter cover crops.
Both will be green and growing in the spring. Oats can be used in the fall
and will winter kill.

Other than rotating patches which I have been doing, is there anything
else I can add to the soil which appears to be getting tired?

Other than adding plenty of compost?

Get a professional soil test that includes the major minor nutrients. That
will indicate what has been depleted in your soil. Then start looking for
more specific answers.

--
Pat in Plymouth MI ('someplace.net' is comcast)

Any technology distinguishable from magic is insufficiently advanced.
(attributed to Don Marti)