Regarding the integration of services and applications, a requisite for the widely deployment of cognitive radio networks is the support of service differentiation to provide a higher reliable service for high priority traffic or nodes. In this paper, we propose a data structure called recovery table which is the set of the channel sensing orders of all cognitive radio links with different priority levels. A central entity (access point) is responsible to fill this table, so it is discussed how by appropriately filling this table, the access point can provide spectrum handover differentiation to increase network availability. As finding the optimal scheme is not efficiently realizable, different heuristic schemes are proposed and their performance is compared.