Please refer to the end of paragraph 2 of the consent-to-publish form:
"Authors may publish an extended version of their proceedings paper as a journal article provided the following principles are adhered to: a) the extended version includes at least 30% new material, b) the original publication is cited, and c) it includes an explicit statement about the increment (e.g., new results, better description of materials, etc.).”
As long as you adhere to these stipulations, we can agree to the submission of your paper to a journal.