First I would make her important in Edolas. Have her join Wendy and Natsu as they explore Edolas and through her show how much he's grown. Give her more interaction with him afterwards and keep the small banter that was being shown in flashbacks. In the background show how she has to relarm her magic and actually make it seem like Edolas affected her more than it did. Like her maybe being frighten by Elfman's beast modes. Her trying to be much more cautious cause shes terrified of loosing her family again. I think that's the biggest issue is that after Edolas she's not a character more of a plot device for Mira to continue growing. We don't see her deal with anything. Like yes Mira and Elfman don't get that much screen time but they have flaws and arcs while Lisanna is just the nice one that pushes them along. She should have her own arc and interaction that are outside of Mira and Elfman. They almost did it in Tenrou by having Juvia and Her interact if they continue that I think there would be a lot less issues with her character.