In what ways can I reduce bleed's duration?
There is no way know to me for players to reduce bleeding duration of bleeding debuffs apllied by enemies directly. The Haemophilia gloves will reduce bleeding duration on enemies (there's a hint to it in their flavor text)
A master artist takes his time when he's painting. Unfortunately, my kind doesn't often have that luxury.
- Coralito, Brotherhood of Silence
However there is a solution to dealing with your problem of handling bleeding stacks and/or duration:
Use flasks!
Flasks should be used pretty much with a 100% uptime and having either an offensive or defensive flask with the suffix "of staunching" is almost necessary. This will give you bleeding immunity for the duration of the effect and remove all currently existing stacks.
Yoke of Suffering provides "30% reduced Duration of Ailments on Enemies", which works on bleed. Although the mod specifies enemies, I believe it will work on bleeds you reflect onto yourself via The Golden Rule (since they are copies of the bleeds you inflict on enemies).
Swift Affliction support will reduce the duration of your bleeds if you use it supporting the skill that inflicts the bleed, although giving up a support gem slot for this is a very expensive sacrifice to make.
Finally, anything that causes your bleeding or ailments to "deal Damage X% faster" will reduce its total duration, as clarified by Mark (GGG dev) in this post. There are too many sources of this to easily list, but just going to the wiki page for Bleeding and ctrl+F'ing "faster" will find you most of them.
Aside from that direct answer to your question, I have to ask - why are you even running into this problem in the first place? The base duration of bleed is 5 seconds. The base max duration of a leech instance is also 5 seconds. Unless you're somehow increasing the duration of your bleeds, or inflicting bleeds with hits that leech less than 10% of your life pool (which would surprise me, player damage is usually vastly larger than player life pools), your leech stacks and your bleeds should be expiring at the same time.
Why are your bleeds outlasting your leech stacks in the first place?