13:10 Why are Tefillin described as a chok when the reason has already been given (remembering exodus –see Ramban)? Ohr Hachaim to Vayikra 26:3 (25th reason) says it refers to wearing Tefillin all day long, but I don’t know if this answers the question. Perhaps the chok refers to the Korban Pesach.
You are correct in your assumption that it is reffering to the korban pesach, as there are some tanaim (Minachot 36b) that learn this way. in fact, the simple meaning in the verse hints that it s referring to the korban Pesach as it says, “from year to year”, this refers to a yearly mitzvah. See Rashi.