Bulk Edit Published Date

Hi

I’m using a theme called Directory2 which has custom posts called Listings. A bunch of them seem to have reverted to an old publish date of 1970(!). I have hundreds of them, is there any way I can bulk/mass change them to a more recent date or even today’s date?

I’ve looked for plugins but the ones I have found don’t seem suitable because I’m using custom posts….

Thanks

Clare