We have indeterminateness of type
0/0,
i.e. limit for the numerator is
$$\lim_{x \to 1^+}\left(1 - \sqrt{x}\right) = 0$$
and limit for the denominator is
$$\lim_{x \to 1^+}\left(1 - x\right) = 0$$
Let's take derivatives of the numerator and denominator until we eliminate indeterninateness.
$$\lim_{x \to 1^+}\left(\frac{1 - \sqrt{x}}{1 - x}\right)$$
=
$$\lim_{x \to 1^+}\left(\frac{\frac{d}{d x} \left(1 - \sqrt{x}\right)}{\frac{d}{d x} \left(1 - x\right)}\right)$$
=
$$\lim_{x \to 1^+}\left(\frac{1}{2 \sqrt{x}}\right)$$
=
$$\lim_{x \to 1^+} \frac{1}{2}$$
=
$$\lim_{x \to 1^+} \frac{1}{2}$$
=
$$\frac{1}{2}$$
It can be seen that we have applied Lopital's rule (we have taken derivatives with respect to the numerator and denominator) 1 time(s)