In the sense of improving by restoring or remodeling, recondition and renovate are interchangeable: "The new owner will recondition (or renovate) the house." Recondition is a somewhat stronger word than renovate, implying a more thorough overhauling or more extensive alterations. Having a hat cleaned and blocked results in a renovation. Having an automobile overhauled is a reconditioning process. Renovate has the added meaning of "to revive," "to impart new vigor to": "The physician claims that a long vacation will renovate you."
Dictionary of problem words and expressions. Harry Shaw. 1975.