Posted: 22/08/2015 at 18:36
Even if it doesn't come back now, the roots should still be OK. I've had clems come back from the dead after 2 years of inactivity, especially group 3s. They can also take a year or two to get their roots well established before putting on lots of lovely flowering top growth.
Feed it next spring in late Feb with slow release clematis food and start with the wildlife friendly slug pellets straight away and sprinkle them very lightly, but regularly every week. If you get a dry spell, give the clematis a good drink of 5 litres or more at a time every few days. Water it anyway with tomato food until flowering starts.