APK Modification before uploading to Play Store - Sign and modify APK Key - App project

Mobile app project description

We have an existing app on the play store that we need to upgrade. I have a new APK although it has the following errors when I upload it to the play store. I do not have the existing or new code so just need a quick modification.

Upload failed
You uploaded an APK signed with a certificate that expires too soon. You need to sign your APK with a certificate that expires farther into the future. Learn more about signing.
You uploaded an APK that is signed with a different certificate to your previous APKs. You must use the same certificate. Your existing APKs are signed with the certificate(s) with fingerprint(s):
[ SHA1: 98:D5:1E:B6:87:CB:A7:4E:DA:96:B9:A2:DD:E1:FD:CA:5B:73:D2:E6 ]
and the certificate(s) used to sign the APK you uploaded have fingerprint(s):
[ SHA1: EC:E5:21:E3:8C:5E:9C:BE:A5:35:03:EA:EF:1A:6D:DD:20:45:83:FA ]