How to make this keep going when you hold down the left mouse button?

It's a chainsaw script, and I'm trying to make it keep going while you're holding down the left mouse button.

r = game:service("RunService")


local damage = 10


local slash_damage = 25

sword = script.Parent.Handle
Tool = script.Parent

Slashing = false

local SlashSound = Instance.new("Sound")
SlashSound.SoundId = "http://www.roblox.com/asset/?id=2766576"
SlashSound.Parent = sword
SlashSound.Volume = 1
SlashSound.Pitch = 1

function blow(hit)
	if (hit.Parent == nil) then return end -- happens when bullet hits sword

	local humanoid = hit.Parent:findFirstChild("Zombie")
	local vCharacter = Tool.Parent
	local vPlayer = game.Players:playerFromCharacter(vCharacter)
	local hum = vCharacter:findFirstChild("Humanoid") -- non-nil if tool held by a character
	if humanoid~=nil and humanoid ~= hum and hum ~= nil then
		-- final check, make sure sword is in-hand
		local right_arm = vCharacter:FindFirstChild("Right Arm")
		if (right_arm ~= nil) then
			local joint = right_arm:FindFirstChild("RightGrip")
			if (joint ~= nil and (joint.Part0 == sword or joint.Part1 == sword)) then
				tagHumanoid(humanoid, vPlayer)
				if Slashing == false then
					Slashing = true
					if hit.Name == "Head" or hit.Name == "Torso" then
						print'CARNAGE!'
						humanoid:TakeDamage(damage)
						Tool.Blade.Hit:Play()
						if hit.Parent:FindFirstChild("Torso") then
							hit.Parent.Torso.RotVelocity = hit.Parent.Torso.RotVelocity + Vector3.new(math.random(-30,30),math.random(-30,30),math.random(-30,30))
						end
						Tool.Bloodeh.Bloodieh.Enabled = true
						untagHumanoid(humanoid)
						wait(.1)
						Slashing = false
					elseif hit.Name == "Left Arm" or hit.Name == "Right Arm" or hit.Name == "Left Leg" or hit.Name == "Right Leg" then
						print'Limb-Taking!'
						humanoid:TakeDamage(damage * .8)
						Tool.Blade.Hit:Play()
						if hit.Parent:FindFirstChild("Torso") then
							hit.Parent.Torso.RotVelocity = hit.Parent.Torso.RotVelocity + Vector3.new(math.random(-15,15),math.random(-15,15),math.random(-15,15))
						end
						Tool.Bloodeh.Bloodieh.Enabled = true
						untagHumanoid(humanoid)
						wait(.1)
						Slashing = false
					else
						print'ARMORED...'
						humanoid:TakeDamage(damage * .2)
						Tool.Blade.Hit:Play()
						if hit.Parent:FindFirstChild("Torso") then
							hit.Parent.Torso.RotVelocity = hit.Parent.Torso.RotVelocity + Vector3.new(math.random(-5,5),math.random(-5,5),math.random(-5,5))
						end
						Tool.Bloodeh.Bloodieh.Enabled = true
						Tool.Bloodeh.Materialleh.Enabled = true
						untagHumanoid(humanoid)
						wait(.1)
						Slashing = false
					end
				end
			end
		end
	elseif humanoid == nil and hum ~= nil then
		if hit.Transparency ~= 1 and hit.CanCollide ~= false then
			Tool.Bloodeh.OtherMaterialleh.Enabled = true
			Tool.Bloodeh.Materialleh.Enabled = true
		end
	end
end


function tagHumanoid(humanoid, player)
	local creator_tag = Instance.new("ObjectValue")
	creator_tag.Value = player
	creator_tag.Name = "creator"
	creator_tag.Parent = humanoid
end

function untagHumanoid(humanoid)
	if humanoid ~= nil then
		local tag = humanoid:findFirstChild("creator")
		if tag ~= nil then
			tag.Parent = nil
		end
	end
end


function attack()
	damage = slash_damage
	SlashSound:play()
	Slash()
end

function Slash()
	Tool.GripForward = Vector3.new(-1,0.2,0)
	Tool.GripPos = Vector3.new(0,0.1,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.4,0)
	Tool.GripPos = Vector3.new(0,0.2,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.5,0)
	Tool.GripPos = Vector3.new(0,0.3,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.8,0)
	Tool.GripPos = Vector3.new(0,0.4,0)
	wait()
	Tool.GripForward = Vector3.new(-1,1,0)
	Tool.GripPos = Vector3.new(0,0.5,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.8,0)
	Tool.GripPos = Vector3.new(0,0.4,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.6,0)
	Tool.GripPos = Vector3.new(0,0.3,0)
	wait()
	Tool.GripForward = Vector3.new(-1,0.4,0)
	Tool.GripPos = Vector3.new(0,0.2,0)
	wait()	
	Tool.GripForward = Vector3.new(-1,0.2,0)
	Tool.GripPos = Vector3.new(0,0.1,0)
	wait()	
	Tool.GripForward = Vector3.new(-1,0.0,0)
	Tool.GripPos = Vector3.new(0,0,0)
	wait()
end

Tool.Enabled = true
local last_attack = 0
function onActivated()

	if not Tool.Enabled then
		return
	end

	Tool.Enabled = false

	local character = Tool.Parent;
	local humanoid = character.Humanoid
	if humanoid == nil then
		print("Humanoid not found")
		return 
	end

	attack()

	wait(.1)

	Tool.Enabled = true
end


function onEquipped()
	sword.Start:Play()
	sword.Idle:Play()
end

function onUnequipped()
	sword.Idle:Stop()
end

function stopTouching(hit)
	if (hit.Parent == nil) then return end
	local humanoid = hit.Parent:findFirstChild("Zombie")
	if humanoid~=nil then	
		if hit.Name == "Head" or hit.Name == "Torso" or hit.Name == "Left Arm" or hit.Name == "Right Arm" or hit.Name == "Left Leg" or hit.Name == "Right Leg" then
			wait(.5)
			Tool.Bloodeh.Bloodieh.Enabled = false
		else
			wait(.5)
			Tool.Bloodeh.Bloodieh.Enabled = false
			Tool.Bloodeh.Materialleh.Enabled = false
		end
	else
		if hit.Transparency ~= 1 and hit.CanCollide ~= false then
			Tool.Bloodeh.OtherMaterialleh.Enabled = false
			Tool.Bloodeh.Materialleh.Enabled = false
		end
	end
end


script.Parent.Activated:connect(onActivated)
script.Parent.Equipped:connect(onEquipped)
script.Parent.Unequipped:connect(onUnequipped)


connection = Tool.Blade.Touched:connect(blow)
Tool.Blade.TouchEnded:connect(stopTouching)

Not going to implement it in the script but use the MouseButton1Down and MouseButton1Up events :)