When you say you go back into the eCart Object to view it and its gone, what do you mean? Is the UPS shipping rule not there or is the addition not there?
When you want to add 15% to your shipping charge, you can try setting up to use times instead of add and set the value to 1.15. I'll attach a screen shot so you can see how it is set up. Once you've applied the 1.15, try hitting tab to set the focus to another field before hitting ok.
If you're still having trouble with adding the rule, please explain in more detail what steps you are taking.