Depends on the relationship between your contexts. If there is a parent child relationship that the child can see the parent but not vice versa. Assuming the beans are in the same context (not the same as the same .xml file) then you should be able to just use
from the reference docs
Specifying the target bean through the bean attribute of the <ref/> tag is the most general form, and
allows creation of a reference to any bean in the same container or parent container, regardless of whether
it is in the same XML file. The value of the bean attribute may be the same as the id attribute of the
target bean, or as one of the values in the name attribute of the target bean.
Alternatively if your second second application context is just a new file you created to split things up you will need to import it.