We have previously proposed an hierarchical mobility management scheme, based on Hierarchical Mobile IPv6 (HMIPv6), to manage the mobility of Mobile Terminals (MTs) in a decentralized manner. Our scheme manages the mobility of an MT using a mobility management router, with a management domain suitable for efficient decentralized load management, Our scheme estimates the speed of the MT, and then estimates the mobility of the MT based on the estimated speed, in order to achieve the objective. Recent simulation results indicate that our previous scheme experiences two problems when estimating the mobility of MTs: the speed of an MT may be misestimated in some cases; and changes in the mobility of an MT may not be noticed when the MT decelerates and stays in the same access area for a long period. This paper proposes an enhanced method that is able to estimate the speed of MTs more accurately, and can persuade decelerated MTs to degrade their mobility management router quickly. Simulation results show that this enhanced method allows our scheme to estimate the mobility of MTs more correctly, and so achieve more efficient load sharing.