Previously analyzed tracks can be re-analyzed by dragging the track, selection of tracks or entire Crate to the Analyze Files button. To force Serato DJ Pro to re-analyze ALL files in your library, hold control while clicking on the analyze files button. 

NOTE: Re-analyzing will not analyze any Locked tracks. You should make sure the Set Beatgrid/ BPM boxes are checked if you wish to re-create Beatgrids.