Can you file an open-ended IFR flight plan?
If operating within a single area (TRACON) then file from KABC -&gt; KABC and in remarks put &quot;Practice APCHS KXYZ KDEF&quot;.  The controller will be asking you what your next approach will be at some point.
Another tactic is to file to ABC VOR (or some other fix) and request a hold. I like this method, as the student gets a hold with an EFC and that gives me time to decide how many orbits they will need as well as the next approach request. I normally have the student ask for the next approach, as it keeps their workload up.
The first suggestion is generally preferred because in the event of lost com, in a true IMC environment, it is clear that you will be returning to KABC, unless you encounter VFR first.
Remember that an IFR clearance can end at a fix (even a pilot defined fix) and when you are in VMC that can be useful. Similarly, an IFR clearance can begin at a fix, and that can be accomplished in a non-radar environment.
Addendum #1
Frequently this type of plan is often referred to as a tower clearance, or if it spans TRACONs it may be called a tower-to-tower.  However, where there are no local approach facilities, center handles this type of clearance as well. Other than just normal approach practice, an area clearance is used to permit photographic missions with cloud cover and instrument student experience with lake effect icing.  For example, a photographer wanted photos of a water fall, through an opening in the clouds.  We got on top, stayed IFR, and maneuvered for his shots.