A person is commanded to remember leaving mitzrayim as if it happened to him every single day. This leaving of Egypt isn't a physical redemption, but a spiritual one. Each day we wake up, a Godly soul in a physical body. Our bodies, in our current position hide HaShem's reality from our perception, but they cannot hide that reality from our souls. Whenever and wherever we desire to be united with HaShem, immediately the union takes place. Though, our senses aren't refined enough to experience it, our souls revel in it.
Our forefathers had to labor intensively to achieve this union, why is the situation so different for us? When HaShem gave us the Torah on Har Sinai, He gave us Himself within the Torah. Since Har Sinai, whenever we seek HaShem out, and desire His closeness, we are united with Him.
When we acknowledge HaShem's oneness and rulership over us, by reciting the Shemah Yisrael, we perform this union. In this way, every day we are brought out of the exile in Egypt and rejoined with HaShem. This is why, the Baal HaTanya says, we say the third chapter of Shemah along with the first two, even though it is a separate mitzwah, because it is [in terms of the union that takes place] one and the same with acknowledging the unity of HaShem.