add_filter('frm_field_value_saved', 'my_custom_function', 10, 3);
function my_custom_function($option_name,$opt_key,$field)
{
	if($field['id']==11375) //Change 11375 to the ID of your radio button /checkbox
	{
		$date=date("l");

		if($date =="Tuesday"){ //Change Tuesday to your preferred date

			if($opt_key==0) //Radio buttons are indexed based, so 0 here represents the first option in the radio button
			{
				$option_name=100; //change 100 to value of the first option
			} else if($opt_key==1)
			{
				$option_name=150;
			} else
			{
				$option_name = 250;
			}
		}
	}
return $option_name;
}

The code assumes you have 3 plans with separate values enabled on your radio button. Every Tuesday, the value of each plan will be updated by this code.