It looks like the second time's the charm for Lindsay Lohan when it comes to cleaning up her act. Since checking into Promises over Memorial Day weekend, she's "not talking on her cell, but she is texting," an insider tells In Touch. In fact, the 20-year-old is so serious about staying sober, she's even signed on to the rehab center's extended-care program. "She's really taking it seriously," adds the insider. "It is a phenomenal change that she is going though." We say way to go, Lindsay!