Если дата всегда будет в этом формате, вы можете заменить ее регулярным выражением:
var months = ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
str = "hello there From 2010-03-04 00:00:00.0 to 2010-03-31 00:00:00.0";
alert(str.replace(/(\d{4})-(\d{2})-(\d{2}) (\d{2}):(\d{2})\:(\d{2}).(\d{1})/g,
function ($0, $1, $2, $3, $4, $5, $6, $7, $8)
{
var date = new Date($1, $2, $3);
return date.getDate() + " " + months[date.getMonth()] + " " + date.getFullYear();
})
);
Пример на http://jsbin.com/igeti/