It you don't already know, if might help to understand how ARP works.
A host broadcasts a ARP query, so all hosts on the broadcast domain see the query.
The query basically says, who has IP x.x.x.x?
If there's a host with the sought for IP, it responds.
The response has the host's MAC. So, once the host that made the ARP request receives it, it now knows what MAC to use for an IP.
The requesting host saves the information in a cache, so if it needs to translate an IP to a MAC again, if first checks the ARP cache, and if an entry is found there, for an IP, it uses associated MAC.
Entries in the ARP cache are only retained for a fixed amount of time. Once an entry expires, the host will need to again broadcast a ARP query (as above).
One issue you can run into, if for some reason a host's MAC changes, a host using ARP cache information will attempt to send to the cached MAC information, which results in frames being undelivered. If this happens, the problem will resolve if the cache entry expires, due to being too old, or if you have the host clear its ARP cache.
