It may never get there.
When it stops, because it runs out of sugar (1.000 or below) or because the yeast get too drunk (somewhere else) you can stabilise with sorbate and sulphate and then with the yeast inhibited and sleeping, you can "safely" add sugar to sweeten without bottles exploding.
You can back sweeten with anything sweet, I'd suggest more fruit concentrate.
When it stops, because it runs out of sugar (1.000 or below) or because the yeast get too drunk (somewhere else) you can stabilise with sorbate and sulphate and then with the yeast inhibited and sleeping, you can "safely" add sugar to sweeten without bottles exploding.
You can back sweeten with anything sweet, I'd suggest more fruit concentrate.