In firmware version 6.0 and higher, you can re-fire cues within any script and also assign variable pulse times per cue. This functions in all modules except 18M hardware A units. Please see Hardware Hammered Out for help with determining which device you have.
In firmware version 5.1 and lower, you can only re-fire a cue if it's not the first script in the cobra.csv file. This limitation is because the first script in the cobra.csv file allows the 18R2 to load the script into the modules while arming. This allows you to fire unlimited channels and cues at the same time.
However, in any script beyond the first, you can re-fire cues; but, you are limited to firing no more than two channels in any 0.4s time window. To assist in determining your hardware version, see Hardware Hammered Out. For more information on using multiple scripts, please see our 18R2 Creating and Uploading Scripts User Guide.