The ReNuYuSenso Orb is an aspiration reward from The Sims 2: Nightlife. It allows the user to change their aspiration and turn-ons and turn-offs. Its name is a pun on "Re-New you", because it renews (stylised as ReNu in the item's name) a Sim's aspiration. Using it below the gold aspiration level might result in the user's primary aspiration becoming Grilled Cheese, with no change in Chemistry.
As an aspiration reward, the ReNuYuSenso Orb is quite useful for Sims who want to change their personality, even though it only has 5 uses. The green lights on the front of the Orb indicate how many uses are left, though if an Orb is placed on a business lot, all the lights -- and uses -- will be reset each time a member of the owner's household visits the lot (which may be a glitch, since Aspiration Rewards don't reset their uses).
With The Sims 2: FreeTime, the ReNuYuSenso Orb will also reset the user's secondary aspiration and aspiration benefits. It can also be used to reset the user's secondary aspiration and aspiration benefits without changing his or her primary aspiration and Chemistry. For example, if a retired Sim has aspiration benefits in the Work category, the player may wish to reset that Sim's aspiration benefits so those points can be used in other categories. According to the Prima Guide for FreeTime, using this option below the gold aspiration level may still result in the user's primary aspiration becoming Grilled Cheese.
The ReNuYuSenso Orb cannot be used to change a Sim's lifetime want without changing that Sim's aspiration. If a Sim chooses the same aspiration he/she already has when using the ReNuYuSenso Orb, and does not change Chemistry, nothing will happen, and it will not count against the machine's 5 uses.