It will help to restart testosterone production and bring back size (at end of cycle) or prevent atrophy (swale's protocol). More than likely, you will recover after your cycle eventually no matter what post cycle therapy (pct) protocol you use. It will just take longer and you won't keep as many gains if you don't use Human Chorionic Gonadotropin (HCG) and a good SERM like nolvadex.
The best way to boost sex drive while on is to use testosterone. For most guys, I'd bet there is a dosing of testosterone that maximize libido. And it generally isn't the huge dosings (more like 100-400 mg EW I'd bet).
You have to look at what these drugs do to several major hormones on the hpta axis (shbg, dhea, free test, dht etc). That is why testosterone itself isn' t a perfect libido booster. You can easily optimize test levels, but that often throws a couple of other things out of whack.