I am still able to reach her.
Just like Jericho85 said, you have to be romancing Layla.
Based on my experience, aside from romancing Layla at every choice, key moments for Elena to kiss you during the train scene would be:
- In your first Chemistry class together select: Complain, Meh
- At the Cafeteria select: Intervene (with Zach)
- At Heaven night club: She's cute, (for fun) Joke
After the train scene, keep romancing Layla, don't check their bodies out: Layla or Elena (not enough points yet), make sure you buy her suntan lotion at the beach, select no to tease her about kissing you on the train ride, let her jump off your shoulders in the water, (during the goodbye at the beach, you'll know it worked if she kisses you after Layla kisses you), tell Elena about Lucas attacking you and offer to help Layla, tell Layla about Lucas but also go after Layla in the bathroom, say Elena's hot when you see her wearing her cheerleader outfit for the first time and keep making jokes, joke about Elena being jealous of your matching outfit with Layla, Help Elena by jumping on her back while she's on top of Layla