Lol, respawning xD
Once you go down generally you don't get back up until the end of the battle, you just lay there and look dead. It's why, in Napoleonics anyway, the sides start to lose men when tge battle is in ffull swing. How long you can be laying there depends when you die and how long the battle will take.
For example, in Napoleonics, most of the redcoat units move veeeeeery slowly on the battlefield, so going down early could mean you're laying there a while, especially if the redcoats are supposed to die, because they take their sweet time.
Or they do what they did a Ickworth last year and refuse to die at all.