One of the restaurants I was able to sample while in San Fran was 'Blowfish - Sushi To Die For!' - great food in a funky modern atmosphere, quite loud music, tatooed servers - very NOT traditional Japanese style restuarants.
When the bill came they had a great survey card included - "Blowfish Babble"
It stated - "Ritsu wants to know.......Tell him what's on your mind" and then blank spaces to give feedback on Food, Service, Music and Love Notes to the Chef.
On the reverse was the usual request for contact details to add to the mailing list and an often missed question by restaurants - Birthday'. Simple question - can be used then to personally invite you back.
I remember taking my wife to a nice restaurant close to where we live for a birthday celebration and they failed to ask what the occasion was when I booked or when we arrived - big missed opportunity to make a simple gesture - rose on the table or free drink - and then follow up at the same time next year with an offer to return.
Are you taking every oppportunity to get feedback on your brand? And how are you keeping in touch with former clients or contacts?