lrepeat was defined in TIP 136 [http://www.tcl.tk/cgi-bin/tct/tip/136.html] , 
which has been approved for incorporation into Tcl 8.5.0 .

Eventually, the doc will be here:
http://www.purl.org/tcl/home/man/tcl8.5/TclCmd/lsearch.html

 lrepeat number element1 ?element2 element3 ...?

This command builds up a list by repeating elements.  It will be a part of
Tcl 8.5.0 .  Note that Tcl 8.5 is available in an early developer form from ftp://ftp.tcl.tk/pub/tcl/nightly-cvs/tcl-*gz .  Early access to Tk 8.5 is there as well.

An example of how it will work is

  lrepeat 3 a

 a a a
----
[RS]: Note the possible confusion with [string repeat]'s syntax:
 % string repeat a 5
 aaaaa

----
[FW]: A forward-compatible version for versions before 8.5 is available in [Additional list functions]
----
[Category Command]