Lethargy is something that commonly accompanies PH cycles for many users, so no worries there. As far as adding back in a pre-workout, most would say no, if it contains stimulants, as that will have more of an impact on your blood pressure. I, personally, kept running mine when I ran H-drol and Epi-Strong bridged into one another, and I felt fine, but I also got a few extra bloody noses (blood work came back fine, though). So, for my personal vote, you could add it in, but do so slowly and cautiously.
You can also look into adding something DHEA based to help combat the lethargy, too. Or, even something like maca and/or a sleep-aid product that would give you better energy come morning. If you want something GH related (in the sleep-aid category), I've used both PowerFULL and Somnidren Ultra and enjoyed both (Somnidren a bit more). If you're looking for a strictly sleep-aid product, I've been using Need2Sleep for the past few weeks every other night or so and have enjoyed the rest from it. There are definitely tons of other options out there, but hopefully this helps a bit.
