Update + Exec Procedure

IF @last_reward is not null
   And (@HPOINT / 4000 * 4000) >=0 And <4000
   and (@HPOINT / 4000 * 4000) > @last_reward 
		BEGIN
		BEGIN TRANSACTION;

Na condição de 8.000 pontos, altere para:

IF @last_reward is not null
   And (@HPOINT / 800 * 8000) >=4000 And <8000
   and (@HPOINT / 8000 * 8000) > @last_reward 
		BEGIN
		BEGIN TRANSACTION;

Não testei.

da erro de syntax na condiçao < 4000 e <8000

fiz um teste aqui, acho que resolveu, vou testar mais umas linhas: 

	IF @last_reward is not null
   And (@HPOINT / 4000 * 4000) < 8000
   and (@HPOINT / 4000 * 4000) > @last_reward 
		BEGIN
		BEGIN TRANSACTION;


	IF @last_reward is not null
   And (@HPOINT / 8000 * 8000) < 12000
   and (@HPOINT / 8000 * 8000) > @last_reward 
		BEGIN
		BEGIN TRANSACTION;