When contracts come up for renewal you don't always have to renew and create a new instance of that contract. You can make changes to the existing contract and bump the expiration date out to cut down on the amount of work involved in renewing contracts. Some companies like to create a new instance of their contracts upon renewal, but if this is not a requirement for your company then making changes to the existing contract and bumping out the expiration date is the best way to go.
This method also cuts down on the amount of records in your database. On another note, more and more companies evergreen their contracts (no expiration date). A lot of companies used to set their contract expiration dates to match the lease expiration date for the equipment. But just because a lease is expiring doesn't mean the contract should expire also. The most common reason to set an expiration date on a contract is if the equipment is nearing the end of it's life expectancy. Otherwise, evergreen is the best way to go.