Help Me With Him At A Party?!?

Me and this boy stefan have had an on off relationship for 3 years (as you would see by my other questions) We always have a laugh and always speak to eachother but he is a bit of a manwhore :/ I am going to a party which he will be attending and I want to get on him and get things back on track but I want to get in there first before he gets distracted. Any ideas of how I could be with him first without seeming desperate? Should I ask him if I can get a lift with him? anything would help! thankyou! xxxxx