Here is the biblical answer I've come up with since observant Christians get shy when they realize their favorite time of the year is as uninspired as the Bunny that lays eggs.
Passover never was changed in the bible, Every one in the Bible who wasn't pagan or heathen kept Passover according to the Law of YHWH God in Exodus 12... Jesus, Moses, the Apostles, the prophets, the king's of Israel, the Corinthians (1Cor 5, 10, 11) and so on.
Joh 2:23 Now when he was in Jerusalem at the passover, in the feast day, many believed in his name, when they saw the miracles which he did.
Joh 12:1 Then Jesus six days before the passover...
The only discipes of Jesus who don't keep Passover are Christian's that would rather keep uninspired traditions that never entered in to the mind of God to communicate for his worship.