Let $c_1, c_2$ be lines in $\mathbb P^3$ that intersect at a point $p$. 
Let $\pi_1:X_1 \rightarrow \mathbb P^3 $ be the blow-up along $c_1$, $E_1$ be the exceptional divisor, $c'_2$ be the proper transform of $c_2$ and $l$ be the fiber over $p$.
 
Again let $\pi_2: X_2 \rightarrow X_1$ be the blow-up along $c'_2$, $E_2$ be the exceptional divisor  and $l'$ be the proper transform of $l$.

Then the divisor $D:=n \pi^* H - E'_1 - E_2$ is not ample on $X_2$ for any number $n$, where 
$\pi = \pi_2 \circ \pi_1$ and $E'_1 = \pi_2^* E_1$.  That's because the intersection number $D \cdot l' =0$ is not positive. 
Instead for any fixed positive integers $a, b$ with $a>b$, the divisor $H':=n \pi^* H - a E'_1 - b E_2$ is ample on $X_2$ for sufficiently large $n$.

So I would like to ask if this is generally true.
Let $X$ be a smooth projective variety and $c_1, c_2$ be distinct smooth irreducible subvarieties of $X$ that are codimension two.  
Let $\pi_1 : X_1 \rightarrow X$ be the blow-up along $c_1$, $E_1$ be the exceptional divisor and  $c'_2$ be the proper transform of $c_2$.
 Let $\pi_2: X_2 \rightarrow X_1$ be the blow-up along $c'_2$ and $E_2$ be the exceptional divisor.

For any fixed positive integers $a, b$ with $a>b$, is the divisor $H':=n \pi^* H - a E'_1 - b E_2$  ample on $X_2$ for sufficiently large $n$?