Sacramentals can lose their blessing for a number of reasons.
"Items lose their blessing or consecration if they are desecrated, if they are substantially broken such that they can no longer be used for their sacred purpose, or if they are publicly sold. If an item is sold by one individual to another for only the price of the material itself, that is, if no profit is made, the blessing remains. For example, if you were to give someone a blessed rosary or sell it to him at cost, he would not have to have it re-blessed. If you were to sell a blessed rosary to someone for profit, he would need to take it to a priest to be blessed."
The word desecration is commonly used in regard to churches, altars, chalices, etc.
For churches, altars etc. lose their consecration:
(1) A church loses its consecration or blessing when the building is destroyed either wholly or in greater part, or when an addition is made to it of larger extent than the original edifice. It does not become desecrated:
•(a) if a portion of the walls and roof falls in, provided the main portion stands, or
•(b) if all the interior plastering becomes detached, or
•(c) if all the crosses disappear, or
•(d) if all the walls are gradually renewed, provided on each occasion the old part is greater than the new, or
•(e) if converted for a while to profane uses, provided it is not polluted (cf. Many, De Locis Sacris).
(2) An altar (fixed) loses its consecration:
•(a) by a notable fracture of table or its support; as, for instance, if the table were broken into two large pieces, or if an anointed corner were broken off, or if the support were seriously impaired, or if one of the columns were displaced;
•(b) by removal of the table from its support, so as to disjoint them;
•(c) by displacing the relics, or cover of the sepulchre (cf. Schulte, Consecranda, p. 222).
(3) An altar-stone loses its consecration:
•(a) by removal of the relics;
•(b) by fracture or removal of the cover of the sepulchre;
•(c) by a notable fracture of the stone;
•(d) by breakage of the anointed corner of stone.
(4) As to the chalice and paten, see ALTAR, under subtitle Loss of Consecration.
The Church has a special **Rite for the reconciling of a profaned church. **
"If a church that was blessed is profaned, it may be reconciled by the pastor or by any priest who has his permission, expressed or presumed. The altar should be entirely bare. It should be prearranged that the officiants can conveniently go around the building, both outside and inside..."
There are also special prayers used in the Rite of reconciling of profaned cemetery.
Thus it stands to reason that if sacramentals are desecrated or lose their blessing through whatever means they may be re-consecrated or blessed by a priest.