How do I simulate a dc-dc boost converter in LTspice?
That behavior is normal.  With a simple converter like this, there will be some finite measure of ripple.  Check out the actual change in voltage in the waveform you attached, it varies from about 4.30655 to 4.30663V; .00008V or 80uV.  

Your oscilloscope probably was not zoomed in enough to see this change.  At such a small level the intrinsic parasitics of the wires and nearby metals might even filter such a low level signal even further before the oscilloscope.

In regards to the voltage not changing, I would try building the circuit in the built in circuit module (circuit lab).  It can simulate the behavior.  Just guessing, maybe the frequency of the PWN needs to be changed.  

The MOSFET has a resistance unlike an ideal switch, so it does take more time for the inductor to charge than you may expect.  

You could also try decreasing the size of the capacitor. This will increase the ripple (which is already very small, so being even 10x-100x larger is probably fine, remember small ripple approximation?) but also allow the output voltage to rise easier, since Q=CV, V=Q/C, so the smaller the cap the less charge per change in output voltage.