Consider the circuit shown. You have replaced the resistor R2, and the circuit now has a switching time of about 5 sec, as you can easily calculate...
T = 1.1 × R2C1
= 1.1 × 47,000 Ω × 0.0001 F = 5.2 sec
But what happens if you press the pushbutton switch again after about 4 sec?
Nothing...! You can not influence the switching time. The monoflop switches about 5 seconds after the first signal back to the ground state (OUT = LOW).
This behavior is known as non-retriggerable.
In many situations, this is the desired behavior of a circuit, but not always...