A repeal bill would not be thousands of pages long. A repeal bill can be done in a single paragraph. You put it on Obama’s desk and force him to veto it. Then you call for a vote to overturn the veto. If you lose, then you have at least fired a shot across the bow and forced Obama and his democrat senators to go on the record so THEY own it.
If you start out with piecemeal legislation tying to “fix” it then you are conceding that the law is both constitutional and worth trying to fix. Then when it all goes to Hell, the democrats can blame the Republicans for breaking it.
Not to “fix” but to force him to kill it by sending him the most hated (but key parts that keeps the mess running) to either sign it, and thus killing it, or vetoing it and having the public turn even harder on him and the Democrats.
It isn’t piecemeal for the sake of it. It’s to have him makes a Sophie’s choice. Either tank the Dems further into the ground or tank Obamacare.