I think process simulation gives you great insight into processes that is not possible by just having experience with the equipment alone. If you are currently working as a plant engineer, use the simulator for as many basic tasks as possible: sizing pipes and control valves, rating exchangers and columns, calculating heats of reaction, etc. Do this even if you feel you could currently do it by hand faster. It takes about 1-2 years to get a real profficiency in all the common tasks. As your skills come up, your productivity can really take off.
If you are like 70-80% of chemical engineers, you went to the simulation course but never used the tool and never gained proficiency. Don't worry about any refresher training, just start using today and you will figure it all out pretty quickly.
What type of work you are actually doing now? If you don't work around significant process equipment, it will be extremely lame just simulating hypothetical stuff, and unlikely to really improve your skills. If you are working in a petrochemical industry with varied equipment then start using your Aspen-plus for as much as you can as described above. You should be able to get qualified for a design job easily.
best wishes,
sshep