What you could do is the use the functionality the JSF framework ( on which xpages is build ). The context global can be used to retrieve the request ( getRequest() if im not mistaken ) . In this request exists a method ( getParameterMap()) which contains all the parameters that where send with the request.
Simple iterating over this map will return all the submitted values. This map contains ALL fields that where available at the time of the submit. So the fields generated by the repeater are also available. The only thing you would need to know are:
The ID generated for the repeater by xPages ( something like <viewID>:<repeatID> use firebug to see the generated IDś).
the ID's that where generated from the editboxes inside the repeat. These idś correspond with keys in the parameter map.
Simple reading the values and do a document.replaceItemValue("field",value). Would do the trick here. It is not as easy as you would expect with notes development but it is an option you can consider