to be thinking about something as a possibility (usually used in questions) 'I thought we might eat out tonight.' 'Where did you have in mind?' I think that's probably what he had in mind.
have someone or something on one's mind and have someone or something on the brain (More informal with brain.): to think often about someone or something; to be obsessed with someone or something. Bill has chocolate on his mind. John has Mary on his mind every minute. Karen has Ken on the brain.