I’m sorry to hear she didn’t make it. She was probably too sweet. I had one like that and had to put her in her own 5G tank. She just wouldn’t stand her ground. Yes, please get more plants and fill in all the holes. Get some caves or decor they can hide in too. My girls each had their own cave. There’s a guy on EBay that sells a big bunch of anacharis for $12.99. It’s always healthy and great price. I get enough to put in 5 tanks and a pond. Look him up. His seller name is rolandpre6. If you can’t find him just search for anacharis and look for the pic of a guy holding a big bunch. You can put the anacharis in the substrate or just float it. It’s good to fill in the gaps between plants. Good luck!