The eucharist/sacrifice of the mass makes present the sacrifice on the cross, it isn't a new sacrifice.
>Christ is spiritually and bodily still on this earth
As he said he would be
> I am with you always, to the close of the age.
Matthew 28:20
The Eucharist is his first coming being made present it's not a second one. http://www.therealpresence.org/eucharst/link/e-litur.html
additional stuff if you want to read more
Down in adoration falling,
Lo! the sacred Host we hail,
Lo! oe'r ancient forms departing
Newer rites of grace prevail;
Faith for all defects supplying,
Where the feeble senses fail.
To the everlasting Father,
And the Son Who reigns on high
With the Holy Spirit proceeding
Forth from each eternally,
Be salvation, honor blessing,
Might and endless majesty.