LIMA, Peru—Peruvian presidential candidate Keiko Fujimori extended her lead over her opponent two weeks before residents head to the polls, according to a survey released Sunday.

Pollster Ipsos said Ms. Fujimori has 46.1% support, compared with 41.6% for economist Pedro Pablo Kuczynski. About 12% of respondents said they were undecided or would spoil their ballot.

The...