Methods to measure your cognitive function

I would like to monitor / measure my cognitive function in regular intervals (say every 6 monhts) to see whether it improves or deteriorates over time. We all know that our brains function less good the older we get but what is the best way to really measure it. For example, I do not want to do these classic IQ tests every few months, since most of them follow some kind of pattern and you get better at it over time (i.e. I was much better on the second IQ test I did not because my IQ got higher but simply because I got used to the kinds of questions they usually pose).
For a lack of a better word I would rather like to measure "raw cognitive power" as good as possible. I was thinking something along the lines like remembering long sequences of numbers or something similar.
Are there these types of tests that an individial can take over and over again to see how the brain function develops? I suppose there must be some literature and resources available but I do not know what to look for. Like when someone had an accident or has to take meds that affect the brain, there must be some ways doctors track that.

Your answers are really appreciated,
Neo