Why are my zombies not respawing?

Why are zombies not spawning again after i kill them, i originally used the Destroy(), but it still did not work

they need to respawn a second time, please help

After the first night, they do not respawn after the second night

    local LightingService = game:GetService("Lighting")
    local TIME_DAY = 6 -- hour of night
    local TIME_NIGHT = 18 -- hour of spawn 
    local zombiesActive = false -- This is our debounce

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    local ZombieT1Copy = game.ServerStorage.T1_Group1:Clone()   --PART TO CLONE

    local ZombieT1Group2Copy = game.ServerStorage.T1_Group2:Clone()

        local ZombieT1Group3Copy = game.ServerStorage.T1_Group3:Clone()

            local Zombie_001 = game.ServerStorage.T1_Group1
                local ZombieFolder1 = game.Workspace.WorkspaceEnemys.T1_Midnight_G1
                local ZombieFolder2 = game.Workspace.WorkspaceEnemys.T1_Midnight_G2
                local ZombieFolder3 = game.Workspace.WorkspaceEnemys.T1_Midnight_G3
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    local function ClockTimeChanged()
        local newClockTime = LightingService.ClockTime

            if zombiesActive then
                -- If zombies are out check if the ClockTime is day.

                if (newClockTime >= TIME_DAY and newClockTime < TIME_NIGHT) then
                        zombiesActive = false
                            -- kill zombie ???

                                        ZombieFolder1:ClearAllChildren()
            ZombieFolder2:ClearAllChildren()

            ZombieFolder3:ClearAllChildren()


                    end    

                elseif (newClockTime  >= TIME_NIGHT or (newClockTime > 0 and newClockTime < TIME_DAY)) then -- If zombies aren't spawned, we check if the ClockTime is night to spawn them.
                zombiesActive = true

            -- spawn zombie
                            ZombieT1Copy.Parent = game.workspace.WorkspaceEnemys.T1_Midnight_G1 

                        ZombieT1Group2Copy.Parent = game.workspace.WorkspaceEnemys.T1_Midnight_G2

                            ZombieT1Group3Copy.Parent = game.workspace.WorkspaceEnemys.T1_Midnight_G3




    end
    end
    LightingService:GetPropertyChangedSignal("ClockTime"):Connect(ClockTimeChanged) --




----   ClonedT1.Position = Vector3.new(123, 123, 123)
                        -- position to use later

THEY NEED TO RESPAWN INFINITLY!