  We use a dynamical model of galactic fountain to study the neutral
extraplanar gas (EPG) in the nearby spiral galaxy NGC 2403. We have modelled
the EPG as a combination of material ejected from the disc by stellar feedback
(i.e. galactic fountain) and gas accreting from the inner circumgalactic medium
(CGM). This accretion is expected to occur because of cooling/condensation of
the hot CGM (corona) triggered by the fountain. Our dynamical model reproduces
the distribution and kinematics of the EPG H$\mathrm{\scriptsize{I}}$ emission
in NGC 2403 remarkably well and suggests a total EPG mass of
$4.7^{+1.2}_{-0.9}\times10^8\mathrm{M}_\odot$, with a typical scale height of
around 1 kpc and a vertical gradient of the rotation velocity of
$-10.0\pm2.7\,\mathrm{km\,s^{-1}\,kpc^{-1}}$. The best-fitting model requires a
characteristic outflow velocity of $50\pm10\,\mathrm{km\,s^{-1}}$. The
outflowing gas starts out mostly ionised and only becomes neutral later in the
trajectory. The accretion rate from the condensation of the inner hot CGM
inferred by the model is 0.8$\,\mathrm{M}_\odot\,\mathrm{yr}^{-1}$,
approximately equal to the star formation rate in this galaxy
(0.6$\,\mathrm{M}_\odot\,\mathrm{yr}^{-1}$). We show that the accretion
profile, which peaks at a radius of about 4.5$\,$kpc, predicts a disc growth
rate compatible with the observed value. Our results indicate that
fountain-driven corona condensation is a likely mechanism to sustain star
formation as well as the disc inside-out growth in local disc galaxies.
