Yes, by repeating it on the track.
There are several ways to do this - the most obvious way is to just copy and paste the “loop”. The usual Ctrl+C (Copy) and Ctrl+V (Paste) keyboard shortcuts can be used.
A quicker way is to use “Repeat” from the “Effect” menu.
If you are creating the loop yourself you can test your loop points by pressing SHIFT+Spacebar to “loop play” the selected audio.
I would highly recommend using Audacity 1.3.12 for any type of music production projects as it is a lot more functional than the old 1.2.6 version.
If you have a loop that has a “decay” (for example a resonant drum or a cymbal) at the end and you want that decay to be included in each loop (and at the end) you could try one of the “Looper-Echo” plug-ins on this page: Nyquist Plug-in: THE KRONx ECHO LOOPER - #2 by steve
If you use either of the two plug-ins on that page, after using the effect please leave some feedback for the plug-in developers on that forum page.