Huh...
I don't recall any epic stuff from Bo9S.
In the baseline epic rules, casters don't gain more spell slots after Caster Level 20, nor do they learn new spells w/o spending feats. Their caster level does increase, though.
So, this argues that the character, once he hit Initiator Level 20, would stop learning maneuvers, and instead just get bonus feats. This is, as above, fairly unsatisfactory.
Within (possibly bent) existing rules, you have a couple of options:
1) Multiclass: Take levels of warblade or crusader, and get more maneuvers known and usable, taking advantage of your level for initiator level on the new maneuvers. Alternately, pick up spellcasting or feats or other abilities that complement what you have.
2) Make epic maneuvers: Make a version of epic spellcasting, called epic initiation or something. Create epic-level manuevers, using existing regular maneuvers as guides and going for a suitably cinematic feel*. Granted, the epic spellcasting rules are widely considered to be broken, but assuming both you and the DM are reasonable, you can probably come up with something decent. It would likely be a lot of work, though.
Brad
* - For ideas, I'd check out anime, Exalted martial arts charms, and the like. An example Stone Dragon maneuver might cause earthquakes in the target(s) squares and hit them with flying shards of rock at the same time. A Shadow Blade technique might spew forth Con drain and negative levels in an area of effect, reducing the targets to husks.