I like the concept of recovering from a Feint. Douglas Cole presented one way to do this in his post on Viking Shield Fighting. I think it could use a tweak or two, but I think this is a good, playtest-ready rule:
You can attempt to recover from the penalty inflicted by a successful Feint against you. Roll against your own weapon skill, using the same statistic used to counter the original Feint (ST or DX for a Beat, DX for a Feint, IQ for a Ruse.) Apply your margin of success against the penalty imposed by your opponents feint, negating the penalty on a one-for-one basis. This never provides a bonus.
Example: Sir Agrippa uses a Beat against Sir Ferro's rapier. Sir Aggrippa has Rapier-16 and makes his ST-based roll by 5, Sir Ferro has Rapier-15 and makes his DX-based roll by 1 and is at -4 on the next turn. Sir Ferro takes a Feint (Recovery) on his next turn, and rolls against his Rapier-15. He rolls a 12, making it by 3. Sir Agrippa's Beat only imposes a -1 to Sir Ferro's Parry the next turn. Had Sir Ferro rolled, for example, a 5, his margin of success would have been 10. He would remove the entire penalty for the Beat, but not gain any bonus to defend.
Notes: One issue with this is whether this is a Ready (you're spending a turn to recover) or it's a variant Feint used to just reset yourself in position. This is an issue because of the rules for Feints and Multiple Attacks (GURPS Martial Arts, p. 127). If you can swap in any kind of Feint for an attack (even part of a Rapid Strike), then you should be able to do a Feint (Recovery) as well.
The downside to this is that it makes Feints even less useful against foes with Multiple Attacks (just swap in a Recovery, every time) and useless against high-skill foes with multiple attacks from any source. The upside is this makes high-skill multiple-attacking martial artists, swashbuckler-types, wuxia swordsman, and chambara movie samurai able to engage in really cinematic combat. It also means feints are a very useful way to deal with multiple-attacking skilled foes, if you're skilled as well - make your Feint, force them to choose between an attack or undoing the Feint. So attacks and feints and attacks and recoveries are all meshed together in a web of action economy until someone cracks.
Making a Ready means it takes your whole turn to avoid suffering from the Feint.
Making it a Ready is probably the most conservative approach, and imposes the most cost.
If you play with hidden feints, like many do, this is pretty much useless unless it's a Beat (which is always obvious.) So you'll need to allow people to notice a feint.
At the beginning your next turn after your opponent has attempted a feint, roll against your best Per-based Melee Combat or Unarmed skill. If you succeed, you know your opponent has attempted a Feint. You don't know how much the contest was won or lost by, however - it won't be resolved until your opponent's next turn. If you take a Feint (Recovery) action, resolve it first and apply your margin of success against the results of the Feint normally.