praise him in the media..although that very rarely works, there is a small chance that it might, and praising him (not incessantly) does no harm. Also, keep tabs on him and keep checking whether or not he'll get into contract negotiations with you...the situation might keep changing, and sometimes you have to nab the player at the exact right time.
Dont worry mate. i presume ur on an early lfc marshall update like i was. I was liverpool and for months i approached him - nothing. But as soon as he was actuallu a free agent in the summer, then he was willing to talk.