。
I agree with you on the point that we should do it once more.
Literal
Us [subject-が] once-more do-[should-べき]-[is-だ] [quotative-と] [say-いう] point [for-では] you [to-に] agree.
~べきだ ('should, ought to') expresses moral obligation or recommendation. という点 ('the point that X') uses the quotative と + いう + 点 to form a specifying noun phrase — 'the point where/that X.' では marks the scope of agreement ('as for that point'). Final 賛成 without copula is elliptical — the だ is dropped in casual endings.