  The in-plane resistivity has been measured in $La_{2-x}Sr_xCuO_4$ (LSxCO)
superconducting thin films of underdoped ($x=0.10,0.12$), optimally-doped
($x=0.15$) and overdoped ($x=0.20,0.25$) compositions. These films were grown
on (100)SrTiO$_3$ substrates, and have about 150 nm thickness. The in-plane
conductivity induced by superconducting fluctuations above the superconducting
transition (the so-called in-plane paraconductivity, $\Delta\sigma_{ab}$) was
extracted from these data in the reduced-temperature range
$10^{-2}\lsim\epsilon\equiv\ln(T/\Tc)\lsim1$. Such a
$\Delta\sigma_{ab}(\epsilon)$ was then analyzed in terms of the
mean-field--like Gaussian-Ginzburg-Landau (GGL) approach extended to the
high-$\epsilon$ region by means of the introduction of a total-energy cutoff,
which takes into account both the kinetic energy and the quantum localization
energy of each fluctuating mode. Our results strongly suggest that at all
temperatures above Tc, including the high reduced-temperature region, the
doping mainly affects in LSxCO thin films the normal-state properties and that
its influence on the superconducting fluctuations is relatively moderate: Even
in the high-$\epsilon$ region, the in-plane paraconductivity is found to be
independent of the opening of a pseudogap in the normal state of the underdoped
films.
