Nettle that won't finish

 We are new to wine making, have done a few kits and wanted to try some 'Country' or 'Hedgerow' recipes..... did Parsnip & Banana.... OMG to die for, 14% of pure heaven in a jar, none of the bottles survived past a week.....sorry I digress, well we also set off some Nettle and after 4 weeks it stopped, we got all excited and I stuck the hydrometer in it and it floats at 1080. The liquor is gorgeous; to be honest we nearly drank it because it seems powerfully strong already! Anyway, did some reading, spoke to a shop and decided it needed to be started again so I put warm water in a glass, added a teaspoon of yeast, sugar and yeast nutrient, covered in Clingfilm for 30 mins. and added it to the nettle demijohn. Fermentation started and ran for about 2 weeks then stopped, the reading was 1060! So I read some more and decided it needed restarting seriously, so I made up the juice of 3 oranges, water, yeast, nutrient and waited 4 days fill it was completely active, then I added some of the nettle, about 50% to 100% starter, left it 2 days till it was really going again, kept this up over about 8 days until I had all of it working again, 4 days later it stopped. 1040!
I added 1lb sugar as was suggested somewhere and bought a heat pad, now at 24c it started again on its only and went for another 6 days, now its 1060 again! It smells divine and tastes wonderful, its murky and has a dangerous feel to it  :twisted: …….. what do we do?

Thanks for the advice, unfortunately I didn't have a hydrometer then so I don't know what the reading would have been. I don't know if you can taste the alcohol, but if you can i would say its high. It has the same feel that the beetroot does and thats 18%.
I have 2 sachets of Restart yeast now.....would that be a high tolerance one?

Hurray its going again and its bubbling like hot spring!!
I realised that the alcohol is killing the yeast so i spread the demijohn across to another so i had 4 pints in each, then put half a 5 gallon restart yeast into each and topped with water.... ironically one started and the other didn't! So I used a third jar to take half out of the working one, and topped it with half of the non-working one, then poured the other halves back together...shoved on the heat pad and hey presto next day i have both going like mad things. I only hope it tastes alright when finished