LCD keypad shields typically have spare holes for connecting sensors etc., and most of the pins thereon are there for that purpose.
You can even rewire the shield to use other pins, but you are most unlikely to need to do that unless you use an ethernet shield as well, and LCD uses pin 4.
You could put another shield between Uno and LCD shield for the sensors, but it is not really necessary.
In short, don't panic.
PS Other than perhaps pin 4, don't be tempted to cut any pins off the LCD shield. There is usually a better solution.