A new fit of diffractive parton distribution functions (DPDFs) to the HERA inclusive and di-jet data in diffractive deep-inelastic scattering (DDIS) at next-to-next-to-leading order accuracy (NNLO) is presented. The inclusion of the most comprehensive dijet cross section data, together with their NNLO predictions, provides enhanced constraints to the gluon component of the DPDF, which is of particular importance for diffractive PDFs. Compared to previous HERA fits, the presented fit includes the high-precision HERA II data of the H1 collaboration, which corresponds to a 40-fold increase in luminosity for inclusive data and six-fold increase for di-jet data. In addition to the inclusive DDIS data sample at the nominal centre-of-mass energy $\sqrt{s} = 319$ GeV, H1 data at $252$ GeV and $225$ GeV are included. The extracted DPDFs are compared to previous DPDF fits and are used to predict cross sections for a large number of available measurements and differential observables.