The roots should produce a new shoot with time. Just keep the plant cared for as normal, but do not fertilize. The only thing that could cause a problem is if your grape plant was a variety that had been grafted onto a rootstock. In that case, the new shoot that stems from the roots may not be the same as the grape variety you had been growing previously. If the vine was cut above the graft, then as long as the new shoot also comes from above the graft, you will end up with the same variety.
The roots should produce a new shoot with time. Just keep the plant cared for as normal, but do not fertilize. The only thing that could cause a problem is if your grape plant was a variety that had been grafted onto a rootstock. In that case, the new shoot that stems from the roots may not be the same as the grape variety you had been growing previously. If the vine was cut above the graft, then as long as the new shoot also comes from above the graft, you will end up with the same variety.