You do not need to register before every election. If you have not moved and you vote at least once every 4 years, you are qualified to vote in all elections in which you are eligible.
If you need to change your name, address, or affiliation for voting purposes, simply fill out a new registration form and return it to the Board of Elections at least 25 days before an election.
You cannot transfer your registration to another county or state. When you move you will need to register at your new location. Cancellation of your prior registration will be part of that process.