Will my previous submissions reload to google sheet if I will re-integrate the form?

If I delete my google sheet integration and re-integrate it, will my previous submissions reload into the sheet?

some submissions are not showing up

Yes, all your form submissions will be added to the new sheet that will be created. Please note, you cannot select the same sheet when re-integrating. 

This is now fixed. Your Google spreadsheet should now update normally as usual.

However, submissions made before the fix might not be added on the sheet so we suggest to re-integrate your form to Google spreadsheet to sync all your form submissions data.

If you have further questions, let us know.