I'm really sorry to hear that. Chronic anxiety can be debilitating. No idea why it would return. Maybe some tolerance to Lorazepam has developed? I don't know what would help reverse or reduce the tolerance.
Have you ever tried Passion Flower? I bought it a few months back when it was on sale on iHerb. It's been quite effective for my anxiety and works on the first day. Though, as with other substances that decrease my anxiety, I get apathetic after a few days on it. So I typically take it once a week or so.
A study found it safe to use with Sertraline for Generalized Anxiety Disorder:
This study noted that passion flower might be suitable as an add-on in the treatment of generalized anxiety disorder with low side effects. Further studies with longer duration are recommended to confirm the results of this study.