I was going to suggest similar to Moonlight - what are his other day naps like now? If he's going to bed at 6.30 he probably should be awake from at least 3pm. Or if he's on 2 naps, then I would also suggest a slightly later bedtime.
At this stage my DS was doing (approx) - wake at 7, nap at 9.30 for an hour, awake until 2, sleep until 3.30, bed at 7.30.
Also, how is he waking? If he is just murmuring, what happens if you just leave him to settle back by himself?
We did a technique (although this was for getting him off to sleep in the first place) where we would put him down and say "it's sleep time now", then go. If he cried, I left him for 3 mins, then went back in, laid him down in the dark and just quietly said "sleep time now". I would do this 3 times and if he was still crying I would pick him up for a hug. I just repeated that until he was asleep.
It might not work for you if you don't like the idea of leaving to cry at all - with DS it wasn't a huge wail, it was obvious tired cry and when I would pick him up it seemed to ramp him up anyway.