You can continue to submit, then if get audited, just tell them you lost that receipt, say sorry politely and you just need to pay that's amount X your tax bracket.
Few times already I been on this(with intention)

But, the bad is they may audit your past 7 years records, this is something really can make you headache

Nope, worst case just say that receipt missing and pay that rm40's tax bracket, case closed.
As said, a word sorry and admit is your mistake is the best way to prevent you from getting penalty.