Cardboard used to starve vines of sun, should I place new soil on it?

Hey guys, after talking with a few people about how to best kill a section of wild grapevine to make way for a bed of chaya/katuk/mexican sunflower/vetiver I decided to use cardboard to starve the area of sunlight. This was about 45 days ago and now 90pct of the vines are dead.

The question is: should I drop new soil or make a lasagna bed on top of the cardboard or should I take out the cardboard and put soil directly on the dead vines, or lastly, should I dig out the old grapevine and start fresh.

This is about 200 sq ft and has four mature pines at its borders. Zone 9b, Central Florida.

45 days doesn't sound long enough to actually kill a grape vine... if you disturb it now and allow light in it might just bounce right back again.

I would keep the cardboard down - perhaps even put a little extra down if there are gaps. You could bring in soil, but you are likely to bring in a host of weed with it. If you have access to mulch material like woodchip I would lay that on top of the cardboard and plant by doing transplants into slits through the cardboard.