Q. Re-prior question on missing words on Hallel, if one by mistake on a day one is supposed to recite the full Hallel only said half Hallel, if already finished, does one have to repeat and recite the brochos again?
A. Poskim disagree. Ribbabos Efraim (4: 105) maintains that if one by mistake on a day one is supposed to recite the full Hallel only said half Hallel, one has to repeat with the brochos.
However, Shevet Halevy (7: 62) asserts that one should repeat without a brocho. He explains that having recited only half Hallel with a brocho, he has complied with the brocho obligation and all he should do is recite again and complete the Hallel but without a brocho.
Ishei Yisroel (41: 36: n. 76) agrees. He adds that Horav Chaim Kanievski Shlit'a wrote to him, that if after ending the half Hallel, he was mesiach daas or became distracted and unfocused on having recited Hallel, he may have to recite the brochos again.
Horav Shlomo Miller's Shlit'a opinion is similar to the last one.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit'a