Replacing text with shortened date and time
It should be like this:

set curr to current date
set dateprint to curr's weekday &amp; ", " &amp; curr's month &amp; " " &amp; curr's day &amp; ¬
" at " &amp; curr's hours &amp; ":" &amp; curr's minutes as string


Or to meet your actual goal:

tell date string of (current date)
set ds to text 1 thru -7
end tell
tell time string of (current date)
set ts to text 1 thru -7 &amp; text -3 thru -1
end tell
set dateprint to ds &amp; " at " &amp; ts as string


Since AppleScript is not case sensitive your script will also replace "time" or "Time" ... so you will need the considering statement:

considering case
set theTime to "TIME"
set finalProduct to replace_chars(pasteboard, theTime, datePrint)
end considering