Maybe that old English lavender in your backyard was a flourishing and flamboyant rock star in its day, but now it's a bit of a wash-up playing county fairs and the occasional Vegas lounge. It's taking up valuable real estate-the sunniest spot in your border garden, but you just don't have the heart to remove it. Or even worse, you can't decide whether or not to remove it.
Sometimes it helps to talk it out with a gardening friend or a gardening professional. If the plant hasn't thrived in years its probably run its course and isn't going to improve. Take it out. If you need a little Irish courage to do this drink a couple of beers before hand-it helps ease the pain.
If you're attached to the plant take some of the blooms or foliage and dry them in that dictionary you never open anymore. Try to fill the space with something that will be meaningful as well-a division from a friend, or that really expensive sheared boxwood Scotty dog you've always wanted.
Gardens can get stagnant and you'll spend less time out there if you keep putting off the inevitable. After the initial pain you'll be really excited about that new space you just opened up.