@Kozzie, I agree with
@VinesnBines -- you started with a low amount of fruit and later diluted it by 40%. At this point you have alcoholic Kool-Aid, and SG is 1.000 in part due to the high amount of water (which has an SG of 1.000). If the wine is sweet, I'd expect it to continue fermentation, but yeast is a living organism and other things in the environment may have stunted it.
I'd go with Option #4. Given the amount of dilution, I don't expect you'll be happy with other options. My suggestion:
Buy a 6 liter kit, doesn't matter what brand. The kit should be diluted to 6 gallons, meaning you need to add ~4.5 gallons of water. However, you've already added 2 gallons of water and started with low fruit, so let's call that another gallon, e.g., treat it as having 3 gallons of water added. So in addition to your existing wine, you only need 1.5 gallons of water.
If you dilute the kit to it's normal level and then mix with your diluted wine, the result will be diluted -- not as much as the original, but at a point you may not like.
Mix the concentrate bag into your existing wine, add 1.5 gallons of water, stir well, and taste it. It's gonna be sweet as it's full of unfermented concentrate, but the overall richness of flavor should be much improved. Add the yeast that came with the kit, and put the wine some place warm, 75 to 80 F. I've had fermentation stick when at somewhat lower temperatures (67 F) that restarted when warmed up.
I don't have a clue what the SG should be -- my best guess is in the 1.050 to 1.060 range.
If anyone has adjustments on this, please chime in.
Couple of points:
Very few grape wines need added water. Grapes are used for wine as they are a complete package, with all constituents in the skin. In some cases the balance isn't optimal for wine, so we adjust, typically sugar and acid.
Rarely water. Other fruits and vegetables do not have the proper water content, so adding water is required. Kits are concentrated, so the added water dilutes them to the correct level.
Once a must is set and the SG is in the correct range (typically 1.070 to 1.100),
do not add water. Kit instructions say to add water to topup -- do this only as an absolutely last resort. Once you add water, removal is not an option.
Ok, adding 1 to 2 cups to a 5 gallon carboy doesn't have much effect. However, adding 1 gallon (20%) will impact the wine. When necessary, top up with a similar or complementary wine whose quality is at or above the wine you're topping up.