I could be missing something, but there are slim pickings near the Lake for Timeshares- at least impressive ones. You might be better off trying Home Away, VRBO, or a realtor for a rental.
When we go to NH, we stay in the Whites at Pollard Brook or South Mountain and travel down to the Lake a few times. We have also stayed at Cold Spring which is a nice small resort in Ashland- close to Squam Lake- my favorite lake in NH.
There is a Windrifter Resort and Misty Harbor Resort, but I have never stayed at either and don't know anything about them.