I simply just run a loop to keep updating the velocity
local BodyVelocity = Instance.new("BodyVelocity")
BodyVelocity.Parent = Character.HumanoidRootPart
BodyVelocity.MaxForce = Vector3.new(500000,1700,500000)
game:GetService("Debris"):AddItem(BodyVelocity , .5)
while BodyVelocity.Parent ~= nil do
BodyVelocity.Velocity = Character.HumanoidRootPart.CFrame.lookVector * 50
game:GetService("RunService").Heartbeat:wait()
end