The English translation of the Me'Am Loez published by moznaim ( a sephardic lidino commentary ) offers two different translations for the word.
One translation is "regret". The other translation is "consolation"
If the word is translated as regret, the commentary says that "[G-d] will not reconsider. [G-d] will not change [His] decree that calls for your destruction. Regret will be hidden from [G-d's] eyes". So that would imply that there is no path for Teshuvah.
If the word is translated as consolation the commentary says that "when [G-d] spoke of the impending plagues you did not heed my words, and so death will afflict you. "Consolation" -- whatever you relied on to bring you consolation -- "will be hidden from [G-d's] eyes" there will be no peace for you.... [G-d] will cut you off."
Also, it looks like Rashi interprets this word for you, and according to the Mikraos Gidolos: IbnEzra, Redak, Abarnbanel, and "all exegates" agree with Rashi:
"Remorse shall be hidden from My eyes: Heb. נֹחַם. I will not regret this evil. נֹחֵם is an expression of regret (נִחוּם) , and the “mem” is a radical like the “mem” of נֹעַם, pleasantness, for the accent is on the first syllable, and the “heth” is vowelized with a “pattah.” Were it an expression of resting (נָח) , with the “mem” serving as a suffix denoting the plural, the accent would be under the “heth,” and it would be vowelized with a “kamatz” [like כֹּחָם their strength; רוּחָם, their spirit.]"