It's absolutely not a "re-enactment".  That implies the Mass is our action. 

Instead, we are being re-presented with a reality that has been going since the Last Supper.

Nothing Jesus did was imperfect.  Nothing short-lived.  All His actions have eternal effects.

To the Father who is not bound in space and time, Jesus is still dying for us, still redeeming us, still resurrecting.

We instead "enter" the Divine Liturgy which is always ongoing.   "Really present."