I deal with the same problem at my unit. We depart our home station (Class C airport, with significant commercial traffic) on an IFR clearance, and then proceed on an IFR route for about 20 minutes before canceling our IFR flight plan and proceeding VFR for our tactical operations inside a nearby restricted area. About 40 minutes later, when we are ready to return, we contact the servicing TRACON to receive sequencing back into the field. This results in one of two things happening:
1. If the inbound traffic flow is light, and the weather is VMC, they'll provide Flight Following and we will recover VFR.
2. If the weather is lousy or the airspace is saturated with arrivals, they will inquire about our previously filed IFR leg and inform us that they "don't show anything in the system." My guess is that as a result of filing the composite IFR/VFR/IFR flight plan, the entire thing was dumped when we initially cancelled IFR.
Typically, after searching the system and coming up empty handed, TRACON will issue us an abbreviated IFR clearance back to the airport. We've found that in order to prevent the plan from dropping out of the system entirely, it is better to file 2 separate IFR legs. On the outbound leg, the last point in our route of flight is the point that we intend to cancel IFR. In the destination block, we put the airfield identifier. That way, if we are approaching our transition point and the weather is VMC we can cancel IFR. If it is not, we are still on an IFR clearance with our clearance limit fix being the field we departed.
We file an entirely separate IFR leg for our return. It originates at the radial/DME fix we intend to recover from and terminates at the field. We have noticed that filing in this manner seems to work better than the composite method.
Hope this helps. Feel free to PM me for more details.