Handling dynamic IPs for clients

Hi all, I have several clients connected to my freeradius server, but these clients have dynamic IPs. I have setup scripts on the clients for sending their IPs to the server and scripts on the server to restart freeradius when an IP address has changed. The problem is that there is always someone that won't be able to be authenticated because the client's IP hasn't been refreshed on the server. Is anybody in a similar situation? If so, do you have a better solution? Thanks. -- Fahd