The Bible speaks of passover in Exodus 13:6-10 saying:
Seven days you shall eat unleavened bread, and on the seventh day there shall be a feast to the LORD. Unleavened bread shall be eaten for seven days; no leavened bread shall be seen with you, and no leaven shall be seen with you in all your territory. You shall tell your son on that day, 'It is because of what the LORD did for me when I came out of Egypt.' And it shall be to you as a sign on your hand and as a memorial between your eyes, that the law of the LORD may be in your mouth. For with a strong hand the LORD has brought you out of Egypt. You shall therefore keep this statute at its appointed time from year to year.
It seems apparent that God intended that we celebrate passover, so as Christians why dont we?