First, make sure that you are using the appropriate media. Does it need acetate, arginine or any other amendments or supplements? Also, Chlamy should never be kept below 16°C.
If there are cells left on the mini slant, add 500 µl of media to the vial and place under the appropriate illumination for 3-10 days until the cells have grown into the liquid. It is a good idea to gently shake the vial 1-2 times a day to help the cells dislodge from the agar. Then, pipette the cells onto a Petri plate containing media + agar. Do not spread it over the entire plate; try to keep it in a concentrated area (~4-6 cm diameter). Allow the liquid media to soak into the agar and keep under the appropriate growth conditions for 1-2 weeks.