Our objective was to compare time to pregnancy after first service for dairy cows managed for second and greater AI services with a program that either promotes insemination at detected estrus (AIE) or timed AI (TAI) after nonpregnancy diagnosis (NPD). After first service, Holstein cows were blocked by parity and randomly assigned to the Day 32 Resynch (D32R; n = 567) or the AIE Resynch (AIER; n = 597) group. Cows in D32R received a GnRH treatment 32 ± 3 d after AI and NPD was conducted 39 ± 3 d after AI by transrectal ultrasonography (TUS). Nonpregnant cows with a corpus luteum (CL) ≥ 15 mm (CL cows) completed the Resynch protocol (PGF_2α-56h-GnRH-16h-TAI). Cows without a CL present at NPD (NoCL cows) were enrolled in a PreG-Resynch protocol (GnRH-7d-GnRH-7d-PGF_2α-56h-GnRH-16h-TAI) to receive TAI. For the AIER group, nonpregnant cows based on TUS 32 ± 3 d after AI and a CL ≥ 15 mm received a PGF_2α (PGF) treatment to induce estrus. Cows not AIE within 7 d were enrolled in Resynch (GnRH-7d-PGF_2α-56h-GnRH-16h-TAI). No CL cows in AIER were enrolled in PreG-Resynch. Cows remained in AIER and D32R until pregnancy or herd exit. Binomial data were analyzed with logistic regression and time to pregnancy [only cows at risk for 200 d after first AI (D32R = 426; AIER = 475)] with Cox’s proportional regression. At NPD, the proportion of CL cows was greater (P < 0.01) for D32R than for AIER (70.3% vs. 62.7%). A greater (P < 0.01) proportion of CL cows were AIE in AIER than D32R (50.9% vs. 5.7%) and P/AI did not differ (P = 0.79; AIER = 36.0% vs. D32R = 35.1%). A greater (P = 0.05) proportion of NoCL cows were AIE in AIER (16.8%) than D32R (9.6%) and P/AI was greater (P = 0.02) for AIER (41.8%) than D32R (31.0%). Overall, P/AI for all AIE and TAI did not differ [P = 0.13; D32R = 34.0% vs. AIER = 38.2%]. The hazard of pregnancy (HR = 1.00; 0.87–1.16) and the proportion of cows pregnant 200 d after first service was similar (P > 0.10) for D32R (88.2%) and AIER (88.0%). In conclusion, a program aimed at increasing the proportion of cows re-inseminated at detected estrus through treatment with PGF at NPD resulted in similar time to pregnancy during lactation than a program that favored TAI after NPD.