Sacrificing priests appear to replenish their blood slaves from the temple, at least for Mictlan, as long as supplies permit: They'll sacrifice down to their sacrifice amount, which is equal to their priest level, +2 for a jade knife, and then just maintain that level of slaves.
Each blood slave sacrificed performs a temple check, which basically has a chance of spreading dominion in the current and neighboring provinces, on outwards. So if you sacrifice 6 blood slaves, such as for a Sun Priest with a Jade Knife, you'll perform 6 temple checks from the sacrifices: A temple check may or may not be successful in raising Dominion, but a sacrifice never really "fails": The priest will always successfully perform a sacrifice. The presence of a temple does not increase your priest's effectiveness at sacrifice: You simply can't perform a sacrifice at all unless you have a temple! Okay, maybe that's an improvement, from 0 to 1.
Search the forum for "temple check" to get formulas on how dominion spreads via temple checks.