It does look good on a resume, but that's about it. Once you are licensed as an RN, that will trump any EMT certification. Even if you were licensed as a paramedic, as well as an RN, if you are working as an RN, you cannot do paramedic-specific skills. For example, if you are working in a hospital or rescue squad as an RN, and you go to a code, you cannot intubate. Even though your paramedic license would qualify you to do this, it is out of the scope of practice for an RN. That is really the only skill that paramedics can do that RN's can't.

Being that you are an EMT-B, this wouldn't really apply anyways, so you really have to look at whether the cost and time for renewing & getting your CEU's is worth it. You can't use the same CEU's for nursing as for your EMT. If I were you, I'd let the EMT certification expire. You can still put it on your resume, just make sure you list the dates you were active.