Some of the fields have lost data after revising the form

There is a form. Some of the data collected. They were to be sent later as were collected offline.
Before sending those forms to server, we have modify the form and redeploy the new version.
now, while sending those previously filled to servers, some of the fields have missing data. Any solution to regain the collected data?

Welcome to the community, @Maitri! Have you gone through this post discussed previously? It should help you get the answer your query: