AES - variable number of encrypt rounds

Cloud service on Java We encrypt data. We want to add encryption rounds to the AES algorithm. At the moment, we use the key length of 256 bytes. We want to do everything is not noticeable. For example, modify system libraries and extension libraries. What we already did: We have already started to solve this problem. Modify two libraries $JAVA_HOME/jre/lib / [login to view URL] and $JAVA_HOME/jre/lib/ext/[login to view URL] Several classes could be modified, mainly constructors, to pass the number of additional rounds to the final com [login to view URL], overcome file hash validation errors and other errors. The JVM is started, tomkat works the app diploidy, the basic functionality works, no errors. But there is a problem with decryption. We encrypted the text file in 2 bytes with two additional rounds. And it's encrypted and decrypted. Then we started encryption-decrypting a small file in a loop. 10 thousand iterations. up to 2000-3000 iteration everything works fine. Then the BadPaddingException error at each iteration. Encryption gives the same result, the hash of the encrypted file is the same. And the decryption just stops working. After restarting the Tomcat, the situation repeats. 2000-3000 iterations everything works, then errors. I note that the undeploy-deploy application does not help, there are errors from the first iteration, if they have already started to pour from the previous application deployment. We need a specialist that could help us to make encryption round number variable.