A few things to try:

Hide - dogs don't like loosing site of their owner!
Sit down on the ground and pretend to be loooking at something really interesting - curiosity might attract her!
Make squeaky/crying noises - same as above.

I've tried all 3 of the above, and with Teagasn, they work!
I also shout 'bye bye', and turn away, and she thinks I am going, so comes running up to me!
When she gets to me, I always make her sit before she can have a treat.

Don't always call her back to put the lead on. Otherwise she won't come back because it's 'going home time'.
Call her back and give her a treat, and let her go again.

yeah hevvur the hiding trick works with my babes, also if i shout whats this!!or biscuit they come running..lol

'whats this' works for Kingsley!!
He comes running!!

well done Jenny and Indie