Thank you for your help. I tried it but it didnt work. I was able to found a solution using below regex.
(?<!Loss )Date : (?:02[/.-](?:[12][0-9]|0[1-9])|(?:0[469]|11)[/.-](?:30|[12][0-9]|0[1-9])|(?:0[13578]|1[02])[/.-](?:3[01]|[12][0-9]|0[1-9]))[/.-][0-9]{4}