The retrial follows the December verdict of Libya's Supreme Court overturning the death sentences for the medics who say they were tortured into confessing.
The allegation is that they deliberately used HIV-tainted blood on children at a hospital in Benghazi in the 1990s.
"The Bulgarian nurses will return home by the end of September, if not earlier," Mr Chaushev of the Bulgarian foreign ministry said.
The six were sentenced to death by firing squad in May 2004 for infecting 426 children with the HIV virus. About 50 of the children have since died. Parents of the inflicted children want the death sentence upheld.
The medics, who have spent almost seven years in prison, say the virus outbreak started before they arrived at the hospital and that they were made scapegoats for poor hygiene.