ליל שימורים הוא לה’ להוציאם מארץ מצרים הוא הלילה הזה לה’ שימרים לכל בני ישראל לדורותם – A night of protection is it unto Hashem, to take them out of the land of Egypt, [such is] this night unto Hashem, protection for all of the children of Israel for all their generations. (Shemos 12:42)
The ba’al haturim writes that the verse repeats the word שימורים – protection – to teach that Hakadosh baruch Hu split the night into two halves, one half for the Exodus from Egypt, and the other half for the future redemption.
Sforno writes that just as Hashem was anxiously awaiting (משמר – שימורים) for the redemption of the Jewish people as long as they were exiled in Egypt, so too He anxiously awaits the future redemption of Israel. He also explains that when the verse says that this night will be for all the children of Israel for all their generations, it means that just as the Exodus occurred in Nissan, so too the future redemption will occur in Nissan (See Rosh Hashana 11A).
The Or Hachaim explains the passuk as referring to five different miraculous events that occur on the night of the 15th of Nissan. 1) Avraham’s victory over the four kings, 2) The Exodus from Egypt, 3) In the days of Chizkiyah when Gavriel struck Sancherev’s army, 4) In the times of Mordechai & Esther when Achashverosh awoke at midnight and 5) The future redemption.
See Shirat Devorah’s post relating to this.