  We report a detailed analysis of the XMM-Newton spectra of six Narrow-Line
Seyfert 1 (NLS1) galaxies at redshift z = 0.35--0.92. Compared with the NLS1s
at lower redshift in the previously most-studied sample, these NLS1s have
larger black hole (BH) masses ($\log\,M_\text{BH}>7.5$) with similar or even
lower Eddington ratios. Our extended XMM-Newton sample of NLS1s shows strong
soft X-ray excess emission below 2 keV. The quantified soft excess strength
does not show an obvious discrepancy from previous studies of the
lower-redshift NLS1s. The systematic effect in the measurement of the Eddington
ratio mainly lies in the bolometric correction factor. We also tentatively fit
the spectra assuming two more physical models for the soft excess: warm
Comptonization and relativistic reflection from the inner accretion disk. In
the first scenario, we confirm the ubiquity of a warm and optically thick
corona. The behavior of a single source can be better explained by relativistic
reflection, although we cannot distinguish which model is a more favorable
explanation for the soft excess based on the best-fit statistics.
