[Dilettante_Pro]

То же самое с одним replace

<script>
    var Amount_of_dogovor = "9 692 978 185,70р.";
    Amount_of_dogovor = Amount_of_dogovor.replace(/ |(р.)|,/g, function (str) {
        if (str == ",") return ".";
        else return "";
    }
    );   //Убираю пробелы, рубли, меняю запятую на точку

    var Test = 100;
    alert(parseFloat(Amount_of_dogovor) + Test);
</script>