Senior Projects Manager | Field & Marten AssociatesNew Westminster, British Columbia, Canada
You have to do risk re-assessment frequently through-out the project because some new risks surface, others are no more valid and so on and this can happen in the risk review meetings which is very important.
Closing risks that are outdated means if a risk in the risk register was supposed to happen at a certain period or time and it did not, then you can re-assess and if the threat is no more valid then you can close this risk and return the contingency allocated to it, if any, or allocate it somewhere else. There is much more to risk management than what is mentioned in the PMBOK, it is a whole filed by itself. Saving Changes...
Rami is correct, risks change over time (added, deleted, changed, mitigated, severity level increased/decreased etc.) and need to be assessed again, hence "re"-assessed. Saving Changes...
The re-assessment of risks is not the execution of the monitoring risk process, but rather, is the re-execution of the identification, analysis, and risk response planning & implementation processes - remember that the PMBOK processes are iterative...