A Renewal is as follows:
If a user with user rights concludes the community needs to take a revoting to decide if he'll or she'll keep the current rights, the user would create an "Renewal" nomination
It lets the community re-decide. A renewal nomination is only to be set up by a user with user rights who wants the community to reassess if they should keep their user rights or remove them.
However: I think this is a flawed system, and believe any user, with enough evidence and commitment can make a renewal for another user, much like a demotion. It's safer than holding up a demotion, and more reasonable, as it let's the community re-decide if they want a user to have rights, rather than a demotion which is a more complicated, war-inducing method. So, that being said, any user who feels like a renewal should be brought up, they should be able to make one, otherwise, likely, a renewal will not be made, as I'm sure no admin, even speaking for myself, if I were in the position, is rational enough to put up a renewal of themself by themselves, and thus it is unlikely for a renewal to happen, even if a good chunk of the community wants it to happen. Giving it only in the call of one person, the user themself, will limit renewals to ever be made, and the community will not get to go through what they believe what must be done.