The overall women's half marathon record of 1:04.31 was set by Ethiopia's Ababel Yeshaneh in a mixed-gender race at Ras al-Khaimah in the United Arab Emirates in February.
Jepchirchir, who held the overall record for two months in 2017, broke away from a small field of nine runners after 20 minutes of the race in the Letna Park and reached the 10-kilometer mark in 30.32 minutes.
She slowed over the second half of the race but was still well inside the previous record.
"I'm satisfied with the result although I thought I could have run 1:04:50," she said. "I was really tired for the last five kilometers."