The best way is to stop memorizing and learn the technology. Sure, if you aren't using it everyday, you will surely lose some memory retention. Try getting on the equipment in your lab and force yourself to use the technology every day. Run some debugs, and try to understand what's going on. The best way to learn is to read the information and then get on the equipment and use it everyday until you are comfortable with it.
With that said, I also believe that no one will ever learn everything, so it's extremely important to know where to find the information as quickly as possible. Ah yes the DocCD. Learn where to find the technologies in question really fast and you can cut down on memorizing things. In today's world, it's not how much you know, but how fast and efficient you are at finding the information you need.
What might help is creating acronyms to remember elections, path selection criteria's and learn those acronyms from the head. Make a large sheet with all kinds of stuff, when you get up in the morning, take some time to learn your sheet. Before you go to sleep repeat it again, no matter how long you studied that day. I am sure that you will know it from the head after 2 months.
If your problem is the fact that you forget IOS commands, my advice would be to keep practicing until you dream IOS.
I think it's also important to make your own notes after you studied a topic. Write down when you read a chapter about a technology with what you didnt know yet and what it does, put it on the sheet that you learn each day. You will notice that after a month or 4 you will laugh at what you wrote down the 1st month.
What worked for me is to explain a technology to a collegue, your wife/girlfriend (if they are interested) or some random stranger . That way you will notice if you understand it or not. If you know the technology you can apply the Einstein one-liner: “If you can't explain it simply, you don't understand it well enough”.