New to LiveCycle JS - need help - how to "Loop" a few fields

Hi,
 
I have a Dynamic form where I have a question which asks users to select a service from a drop down list (3 items)
 
This spawns the sub-form for the selected service. At the end of the sub-form there is a question asking if the user needs any other service, if the user responds "Yes" (from a drop down) the whole process is repeated/looped again... services drop down -> new service sub-form ...
 
Please help me achieve this :)
 
Thanks in advance,
 
Rb