Keeping Relational Table Current-Access 2007

I am creating my first database in Access 2007 and found when completing 
certain fields, my data is redundant.  I thought a good solution to avoid 
typing was to create a new single field table, linking it to my primary
table 
in my database with a many to one relation****p, and then simply clicking
the 
appropriate value(s) from the drop down list in that field.  This worked 
great for the first 20 or so records.  Then I needed new values for that 
field.  I updated the second table with additional records, but can't seem
to 
get them to show in my primary table when choosing to select that field.  

How can I get the additional values to be reflected in that drop down
list?