She underlined her support for a proposal in August by her interior minister, Thomas de Maiziere, to outlaw the full-face burqa Islamic veil in public places.
Next year's polls will "not be a walk in the park" as Germany is deeply polarised, Merkel warned, but urged the population to remain "sceptical about simple answers".
In August, Merkel had said that while she believed the burqa made it hard for women in Germany to integrate, she was more hesitant about suggesting a ban.
Merkel, who is seeking a fourth term in office next year, won 89.5 percent of votes cast by just under 1,000 party delegates at a congress of the CDU in the western city of Essen on December 6.
Merkel is running for a new term as chairwoman for CDU, which will be voted on by delegates after Tuesday's annual conference.
'A situation like the one in the late summer of 2015 can not, should not and must not be repeated, ' Ms Merkel told party delegates at a congress in the western city of Essen.
She also stressed that each asylum request would be examined carefully, and "not all can and will stay" in Germany. Humanitarian groups have praised Germany's intake of refugees. Two years ago, she won the support of 96.7 percent of delegates, one of her best results.
The call comes as Merkel is facing backlash for her "open doors" approach to the refugee crisis. Her lowest was in 2004, when she was approved by 88.4 percent. Merkel wants to secure the backing of her conse. "Our rights have priority over tribal laws and Sharia laws", Merkel said at the conference according to German newspaper Frankfurter Allgemeine.
She deplored the failure of the worldwide community to alleviate the suffering in Syria's besieged city of Aleppo, calling it a "disgrace".
Merkel's speech on Tuesday is likely to be seen as an example of the hard balancing act that she faces ahead of next year's elections.
She also underlined the importance of holding the European Union together, saying Germany will do well "only when Europe does well too".
Merkel believes the ban is part of a cultural revolution where you will be seeing fewer people over time wear them.