First, Roundup needs for the plants to be actively growing for it to
effectively kill them. If the vines are still dormant, it may take
another application. If you try to kill weeds in early Spring or late
fall it's far less effective than if you use it when the weather is
warm and the weeds active.

You can reseed a week after using regular Roundup. Not sure what is
added to the Plus concentrate, so I'd check the label or website.

If applied right, you should be rid of the vines without them
reappearing, but it's always possible a small amount could require
retreatment.