The multisite component is installed and configured successfully. My sites are working fine. But every time my site gets down frequently. when I check the issue from joomla admin panel, The check patches installation shows define.php is not ok. it is giving below status for it.
Not OK

Multisites definition not present
Configuration redefinition not possible
Installation redefinition not possible

Actions:

Add 1 line
Update 2 lines

When I give the permission to this file and click on install button. every files comes in OK stage and My sites also get start working. Then after sometime this case is happening again and again, If I am following the above step the issue gets solved but issue regenerates again and again. I need help to resolve this problem permanently.

I am using below version
Joomla Multi Sites version: 1.2.68 (Latest available: 1.2.72) Get Latest Version
Patches definition version: 1.2.76 (Latest available: 1.2.76)

I don't know who restore the old "define.php" file.
Perhaps that you have a script or backup/restore thing somewhere that restore the file.

All I can suggest you is to try identifying at which moment this happen and try verify the server log file to identify the action that would be performed and that would result to the restore of the "define.php" file.

I suspect for example an update of joomla or an extension that perform security check that would restore automatically the file at a given time or a cron.