Fundamentally, it is a question of discerning what the legislature intended. There are decisions going both ways, but I think the better view is that, consistent with the general policy of 1 U.S.C. § 108, repeal of an amending statute generally would not revive an old federal law.
Crawford, The Construction Of Statutes (1940) at p 641 suggests otherwise:
the repeal of an amendment to a prior statutory enactment restores the prior enactment to the same status which it had prior to the amendment, in the absence of a contrary legislative intent.
The authority cited is In re Lippincott, 119 N.J. Eq. 343 (1936):
Where a statute completely repealing a prior statute is itself repealed the original act is thereby revived … this was the rule of the common law … If such be the effect of the repeal of a repealing act, it seems a logically necessary result, — at least in the absence of some facts or circumstances creating an exception, — that a similar result must be adjudged in the case of the repeal of an amending act. The original act is thereby restored to its original, unamended state.
In Hamar Theatres, Inc. v. Cryan, 365 F. Supp. 1312 (1973), a federal court dismissed an argument by analogy to this decision:
That argument relies upon an analogy to certain old New Jersey cases holding that where a statute completely repealing a prior law is itself repealed, the original act is thereby revived … These cases have been overruled by N.J.S. 1:1-3.2, enacted in 1960.
Note that the court elided the concepts of repeal and amendment. An amending statute can be seen as repealing part of an earlier statute and replacing it with the amended text. It is likely that today’s federal courts would be similarly reluctant to apply the common law approach suggested by Crawford in view of 1 U.S.C. § 108, despite the fact that in terms it deals only with the repeal of a “repealing Act.”
The Supreme Court’s decision in Kohlsaat v. Murphy, 96 U.S. 153 (1877) tends to confirm this. The provision which became 1 U.S.C. § 108 had by then been enacted, “but that provision was not in force when the cause of action in this case arose.” The decision concerned the import duty payable on “cotton canvas cut into strips of the size and shape for slippers,” which was affected by a series of legislative amendments:
In 1861, cloth cut into patterns for slippers was duty free.
In 1862, duty of 10% was imposed on these goods.
In 1864, the specific duty of 10% was re-enacted, but a duty of 35% was imposed on “manufactures of cotton not otherwise provided for.”
In 1867, the paragraph creating the specific duty of 10% was repealed.
The Court held that the 1861 and 1862 laws were not revived, and the general duty of 35% was applicable:
Attempt at one time was made, as indicated in the second ground of the protest, to maintain the proposition that the repeal by the joint resolution referred to, of the enumerating paragraph in the Act of June 30, 1864, revived the same provision in the Act of July 14, 1862, which imposed the same duty as the repealed paragraph … Eminent counsel urged the proposition; but the court held otherwise, for reasons which are entirely satisfactory … the plaintiffs in this case abandon that theory, and rest their case entirely upon the first ground assumed in the protest — that the goods imported are exempt from duty, or, in other words, that the effect of the joint resolution under consideration was to repeal the paragraph in the two prior acts, to-wit, the act of 1864 and the act of 1862, and to revive the corresponding provision in the Act of the 2d of March, 1861, which included such goods in the free list.
Cases arise undoubtedly where it is properly held that the repeal of a repealing statute revives the old law, but the Court is of the opinion that the rule in that regard is inapplicable to the case before the Court … Rules and maxims of interpretation are ordained as aids in discovering the true intent and meaning of any particular enactment; but the controlling rule of decision in applying the statute in any particular case is that whenever the intention of the legislature can be discovered from the words employed, in view of the subject matter and the surrounding circumstances, it ought to prevail, unless it lead to absurd and irrational conclusions, which should never be imputed to the legislature, except when the language employed will admit of no other signification.
The full decision illustrates the ambiguity in the concepts of repeal and amendment, at least in the context of 19th-century legislative drafting practice. It is to be hoped that modern legislatures would be more careful to make their intent clear. But if a similar question did arise today, the court would probably lean towards applying the substance of 1 U.S.C. § 108 even to a statute which does not fall strictly within its terms.