It's best not to try to sell right before your major leases or other key contracts expire. When prospective purchasers look at your business, they'll want to be able to predict what they'll need to spend for rent, labor, materials, supplies, and all the other major items. They won't want to have to renegotiate key contracts right off the bat, or take the chance that a lease may not be renewable at all.
If you must sell right before a contract is scheduled to expire, we suggest that you try to renegotiate it early, so that you'll get a favorable rate (or at least a predictable one) locked in for your purchaser. At the same time, have your lawyer make sure that the contract will be assumable by a new owner, or you'll have gone to a lot of trouble for nothing.