Hi,
here's my opinion about what to cut:
Stoneforge Masterwork - opens to spot removal and helps little to none
Retreat to Hagra - does almost nothing
Shadows of the Past - does almost nothing
Underworld Connections - slow... you can use
Phyrexian Arena for something better and faster
Graceful Reprieve - not much useful... you can use
Unburial Rites,
Faith's Reward or
Rootborn DefensesTouch of Moonglove - does almost nothing
Aphetto Dredging - not much useful... you can use Patriach's Bidding
Feast of Blood - if you are playin it for the life gain, don't. At this point would be better
Terminate or Doom Blade-like
Bloodline Necromancer - slow
Cliffhaven Vampire - slow and does almost nothing
Gifted Aetherborn - useless
Mephidross Vampire - almost useless
Stromkirk Condemned - almost useless and little to none sinergy with the deck
Vampire Nighthawk - useless
Generally speaking, all the cards that let you take creature in your hand from your graveyard are slow or almost useless. I understand that you want to play a sacrifice deck, but it's better sacrifice token instead of creature so it's better embrace the token aspect of the deck instead of a sudo-reanimator.
Last note: i see a lot of heavy mana cards but you are running a low number of lands and little to none mana rocks (or sacrifice altar). Can I suggest to play at least 37 lands and ten mana rocks/altar? A sacrifice/aggro deck without
Phyrexian Altar and
Ashnod's Altar it's strange, and playing more arount sacrifice you can add
Altar of Dementia,
Dictate of Erebos and
Grave Pact for more removal effects.
I hope my opinion would be useful to you