Here is an easy way to force VUE to add more plants. On the density tab you have the slider that maxes out at 100%. Rather than use the slider, manually input a number higher than that and it will force the program to add more than 100%. For example, if set to 100% you hit the populate button and it generates 1000 instances of your ecosystem, input 500 and then repopulate you terrain. While it doesn't give 5 times the original amount it does however force more instances of your ecosystem. Just play around with the numbers and go as high as necessary to fully cover your terrain. Hope this helps