Rip it All Out...or Not?

Planning our fall vegetable garden now...and I'm wondering whether I should just swap stuff out or rip the whole kit-and-caboodle out, add compost, and then plant new stuff? Am reading conflicting information online. And the garden is looking rather tired...

What do you typically do?

Advice is welcome from anywhere, but I'm especially interested for folks in Zones 8 & 9 (no offense zones 1-7!). Although we've raised veggies before, I've never planted a fall garden. Growing up, it was too cool to do it, and our veggies typically lasted into September anyway. Heck, in Louisiana, you could stick just about anything in the ground year 'round. But at night in the Hill Country's Southern tip, it can be several degrees cooler in the evening than the city a few miles away.