Our first recommendation would be to attempt to clean the keyboard. Unfortunately laptop keyboards can be difficult to clean. What you could try is buying a can of compressed air and blow air under the keyboard key to see if it dislodges any dirt or hair that may be causing your issue.
Unfortunately if this doesn’t work apart from having the keyboard replaced or connecting an external keyboard we are unable to think of any alternate solution. We are unaware of any method of re-mapping the enter key.