Unregenerately, which means a stubborn refusal to reform or change, can be substituted with several other synonyms. These synonyms include relentlessly, incorrigibly, irredeemably, inveterately, and recalcitrantly. The word "relentlessly" means something that is done without ceasing or diminishing, while "incorrigibly" denotes a situation that is beyond correction or rehabilitation. Similarly, "irredeemably" refers to a condition that is irreparable or unrecoverable, while "inveterately" refers to a deeply established habit or tendency. Finally, "recalcitrantly" is used to describe someone who is stubbornly disobedient or difficult to manage. Ultimately, all these synonyms can be used interchangeably to describe a situation or person that refuses to change or reform.