No, it is not possible to register for an additional elective in a later block because of (a) failed elective(s) resit(s) in an earlier block.
If you fail (one of) your elective(s) and also failed, the resit(s) you will have to retake the elective(s) in the following academic year.
Note that it is not mandatory to retake the same elective. Depending on the type of elective you still need to complete (MPE/MFE). You can select any elective in any given elective block in the following academic year, taking into account that you can only take one elective per block.
If you have completed all programme components and you failed your MFE, you may explore the options to complete a core course from another MSc Programme of at least 6 EC. In some cases, it may be possible to meet the MFE requirement with a course from another university, of at least 6 EC, provided the Academic Director of your programme and the Examination Board approve the external course. Please be aware that your options to take core courses from other programmes as an MFE may be limited as the core courses usually have fewer credits. More information can be found in the re-enrolment guide.