The reason for the 60% runups before takeoff on the big fan engines is to generate enough air blast (not hot air) to blow small amounts of ice off the innards behind the fan as well as to shed any ice that might have accumulated on the blades or spinner.
Once having been completed, you should be ready for takeoff assuming conditions permit.
One of the problems is that if you delay this runup for too long a time it may actually result in large amounts of ice being shed which could damage your engine. Or if you only use a 50% runup instead of the recommendation assuming that by holding it longer it will melt the ice (definitely this won't work).
The biggest problem with all this is the problem that occurs on taxi in during icing cnditions and nobody notices it behind the fan and then attempts takeoff without applying the 60% runup, poof all the built up ice goes down the engine.
Assuming that you have followed the manual, there should be no problem in continuing the takeoff from your last spoolup.