You can keep doing LST until the branches have small "tufts"/small budlets forming.
After this it is best to leave the plant alone to do her flowering without any external stresses.
Do not untie anything, this will just cause a huge mess with overlapping branches. You have trained your plant a certain way and she is now dedicated to this structure, so now she needs to stay like she is. Besides, why would you want to continue with LST and then untie everything?
Hope this helps,..........
Organoman.