What is the formula for induced drag?
It seem your graph of induced lift is not decreasing because you assume that the lift increases with velocity. This is generally not the case. 

Typically, a drag vs velocity graph is made for unaccelerated level flight. Under these conditions the lift is equal to the weight of the aircraft. 

$L = W =  \frac{1}{2}\rho V^2 c_L S$

From this we can obtain the lift coefficient as a function of velocity:

$c_L =  \frac{W }{\frac{1}{2} \rho V^2 S}$

The drag of the  aircraft is the sum of the parasite drag and the induced drag:

$D = D_p + D_i$

With the parasite drag: 

$D_p = c_{D,0}\frac{1}{2} \rho V^2 S $

And the induced drag:

$D_i = \frac{1}{2}\rho V^2 S \frac{c_L^2}{\pi  AR \epsilon} =
\frac{W^2}{\frac{1}{2}\rho V^2 S \pi AR \epsilon}  = \frac{W^2}{\frac{1}{2}\rho V^2   \pi b^2 \epsilon}$ 

It is important to understand that this only holds when the lift is equal to the weight of the aircraft (e.g. straight &amp; level flight)

Nomenclature:
    $L\:\:\:\:\:$ lift
    $W\:\:\:$ aircraft's weight
    $\rho\:\:\:\:\:$ air density
    $V\:\:\:\:$ velocity
    $S\:\:\:\:$ wing surface area
    $c_L \:\:\:$ lift coefficient
    $c_{D0} \:$  zero-lift drag coefficient
    $\pi \:\:\:\:\:$  3.14159$\dots$
    $AR \:\:$  aspect ratio of the wing
    $\epsilon \:\:\:\:\:\:$  the wing's Oswald factor
    $b \:\:\:\:\:\:$  wing span