regain of land gifted to a charitable trust

Section 126 of Transfer of Property Act, 1882 deals with when gift may be suspended or revoked. According to it, the donor and donee may agree that on the happening of any specified event which does not depend on the will of the donor a gift shall be suspended or revoked but a gift which the parties agree shall be revocable wholly or in part, at the mere will of the donor is void wholly or in part as the case may be. A gift may also be revoked in any of the cases in which if it were a contract it might be rescinded. Such as aforesaid a gift cannot be revoked. Nothing contained in this section shall be deemed to affect the rights of transferees for consideration without notice. Gift is transfer of ownership without consideration. Like other transfers, gift too can be made subject to certain conditions. Donor may make a gift subject to a condition of it being suspended or revoked. But, such gifts would then be governed by those provisions of this Act
which regulate conditional transfers.

Accordingly, if a gift is made subject to condition of it being revoked in future the condition must be valid and enforceable under those provisions. Section 126 lays down two modes of revocation of gift:
(i) Revocation by mutual agreement of donor and donee.
(ii) Revocation by rescission as in the case of contracts. 

If there was a specific clause in the gift deed stating that unfulfillment of certain works or misuse of the property will revoke the deed, it would become much easier to get the property back. 

You have not posted the complete facts.