I was going to say long line too. You can buy horse lunge lines easily. Knot along length to prevent it slipping and burning your hands.
Also consider whistle training - this works well with mine. I use a 210.5 as it's a nice pitch. 2 peeps means come. When the dog comes, vary the reward so he learns when he comes to you he gets something nice, but doesn't know what it is - either tasty treat, or chuck a ball, or tug etc.
Other stuff to try:
Yell 'This way!' turn 180 and run on the spot, the dog thinks you're running away - mine freak at that and come running towards me. This is particularly frightening at night (for me!) as Remus sounds like a horse thundering towards you
Hide - behind a hedge or tree and blow 2 peeps on whistle for the dog to find you.
Practice these things when there's not major distractions to start with so the dog succeeds. Gives any locals a laugh too!