The 25-year-old actress was seen getting cosy with her ex-girlfriend - who she dated for two years from 2007 to 2009 before briefly getting back together last year - at New York nightclub Le Baron earlier this week, and reportedly "couldn`t get enough of each other" while partying the night away.
A source told X17 Online: "Lindsay and Sam were whispering and laughing and they left the club holding hands. They didn`t care who saw them and they definitely seem to be back on. It was just like the old days, they couldn`t get enough of each other!"
Bisexual Lindsay, who recently landed the role of the late Dame Elizabeth Taylor in a new TV movie `Liz and Dick`, was linked to photographer Terry Richardson and porn star Alex Torres in March, but was believed to be trying to stay single so she could focus on her part.
A source said: "Lindsay wants to devote all her spare time to reading the script and getting Liz`s persona down pat rather than focus on a new relationship."