How can I loop the round part of this while saving the dscore.Value and ascore.Value?

Congrats on beginning to script! I'll start by saying that you should definitely have functions here and not just a bunch of free-floating while loops. Furthermore, you should never have more than 1 while true loop. It's difficult to tell what you want with your code, however, I've gone ahead and coded what I interpreted from looking at your code.

I've also reformatted most of your code, hopefully you can see the differences and remember them. The most important would be the unnecessary while true loops that you just end up breaking out of anyway and the false indentation.

local dscore = script.DefenderScore
local s = script.Stat
local ascore = script.AttackScore
local gameStarted = false

-- this is intermission

local function startGame()
    t = 5
    repeat
        t = t-1
        s.Value = "Game Starting In "..t.." Seconds"
        wait(1)
    until t == 0

    gameStarted = true
    s.Value = "Game Starting"
    wait(2)

    for i, v in pairs(game.Teams.Orange:GetPlayers()) do
        v.Character.Head:Destroy()
    end

    for i, v in pairs(game.Teams.Blue:GetPlayers()) do
        v.Character.Head:Destroy()
    end
end

local function checkScores()
    if dscore > 3 then
        s.Value = "Orange Wins The Game" 
        gameStarted = false
    end
    if ascore > 3 then
        s.Value = "Blue Wins The Game" 
        gameStarted = false
    end
end

while gameStarted == true do
    checkScores()
    wait(1)
end

startGame()