The door appeared to be closed on the couple's on-off relationship when they went their separate ways in 2005, amid rumours their 18 year age gap was a factor.
But onlookers are convinced the fling is back on after watching Bullitt actress Bisset, 64, and 48-year-old Boztepe enjoy an intimate lunch at Los Angeles' Villa Blanca on 15 August.
A source tells Star magazine, "Jacqueline was very flirty. She called him darling. They talked very closely and only had eyes for each other."